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The effects of purchasing skill instruction for individuals with developmental disabilities: a meta-analysis.
Abstract:
This meta-analysis examines the effectiveness of functional mathematics instruction, specifically purchasing skill instruction, for individuals with disabilities. Twenty-eight intervention studies were identified and reviewed. Because all studies employed single-subject research designs, a nonparametric procedure, the percentage of nonoverlapping data (PND), was used to estimate treatment effects. Results indicated a moderately positive effect for purchasing skill instruction (median PND = 87%). Maintenance (median PND = 100%) and generalization effects (median PND = 86%) revealed large and moderate effects, respectively. Further categorical comparisons indicated that variables such as participants' entry skills, money skill adaptations, type of purchase, error correction procedure, and instructional setting were related to the treatment effectiveness.

Subject:
Developmentally disabled children (Social aspects)
Developmentally disabled children (Educational aspects)
Teaching (Equipment and supplies)
Teaching (Research)
Authors:
Xin, Yan Ping
Grasso, Edward
Dipipi-Hoy, Caroline M.
Jitendra, Asha
Pub Date:
06/22/2005
Publication:
Name: Exceptional Children Publisher: Council for Exceptional Children Audience: Academic; Professional Format: Magazine/Journal Subject: Education; Family and marriage Copyright: COPYRIGHT 2005 Council for Exceptional Children ISSN: 0014-4029
Issue:
Date: Summer, 2005 Source Volume: 71 Source Issue: 4
Topic:
Event Code: 310 Science & research; 290 Public affairs
Geographic:
Geographic Scope: United States Geographic Code: 1USA United States
Accession Number:
133810385
Full Text:
For adults with disabilities, quality of life is enhanced with improvements in life skills such as social interaction, employment, money management, community adjustment, independent living, self-determination, personal choice, recreation, physical and material well-being, civic responsibility, psychological well-being, and personal satisfaction (Hughes, Eisenman, Hwang, Kim, Killian, & Scott, 1997). However, many individuals with developmental disabilities are not adequately prepared to live and work in their community (Brown, 2000; Frank & Sitlington, 2000; Patton, Cronin, & Jairrels, 1997; Rusch, Szymanski, & Chadsey-Rusch, 1992). With an increase in advocacy for improved postschool outcomes, the importance of preparing students to live independently and interact within their community has gained attention (Lehmann, Bassett, Sands, Spencer, & Gliner, 1999). Further, with the inception of supported employment services in 1986, more individuals with developmental disabilities have entered competitive, employment positions in community-based settings (Revell, Kregel, Wehman, & Bond, 2000).

Competitive employment has, in turn, led to these individuals assuming responsibilities for managing and using money independently (Moon & Inge, 2000). Also, the recent emphasis on self-determination as an important educational outcome has resulted in less reliance on caregivers and a greater focus on facilitating the independence of individuals with disabilities (Agran, Blanchard, & Wehmeyer, 2000; Field & Hoffman, 2002; Zhang & Stecker, 2001). The quality of community integration and participation by individuals with developmental disabilities is seen as a function of independent community competencies (Benz, Lindstrom, & Yovanoff, 2000).

One general set of skills necessary to function successfully in the community is the ability to manage money (Browder & Grasso, 1999). Being able to earn, budget, and spend money is an integral part of independent community functioning. The ability to engage in such skills greatly enhances an individual's ability to independently use various community-based services (e.g., riding public transportation, eating in restaurants, making purchases). The importance of teaching community skills, particularly purchasing skills, has been widely reported in the literature (e.g., Alcantara, 1994). The majority of the research on purchasing skills has focused on teaching essential money skills within purchasing routines.

The need to promote independent purchasing by individuals with developmental disabilities is clear. To date, there have been two major practitioner-oriented reviews of the literature on functional math instruction as it relates to the use of money by individuals with developmental disabilities (Browder & Grasso, 1999; Morse, Schuster, & Sandknop, 1996). Although the reviews have provided some evaluation of the effects of money and purchasing skill instruction or raised issues for consideration, none has offered a comprehensive, quantitative synthesis of the overall effects of purchasing, money skills instruction, or the effects of the various instructional strategies. Rather, the reviews offer information that is important for educators to consider when teaching functional math. For example, Browder and Grasso's review of money skills instruction provided several recommendations for practice, which included (a) simplifying the use of money task with adaptations or bypass strategies (e.g., calculators, money envelopes); (b) providing direct instruction using prompting and fading strategies, such as time delay and least intrusive prompt procedures; and (c) training and assessing generalization in community contexts. In addition, Morse et al. summarized the research on grocery shopping skill instruction for persons with moderate to profound intellectual disabilities. This review identified the need to introduce purchasing skills as early as elementary grades and continue instruction throughout the school years. It also indicated the need to examine the relative effectiveness of various strategies for teaching grocery shopping skills as well as to identify factors (e.g., instructional settings) that promote generalization. Both reviews also indicated the need to go beyond money or purchasing skills and consider other related skills instruction (e.g., social skills, menu planning, nutrition lessons, and checkbook and ATM machine use).

In summary, there are two important reasons to review the complete functional math/money skills and purchasing skills literature. First, the results from studies of money skills and purchasing skills differ in many ways (e.g., type of purchase, participant characteristics), and it is important to assess how and to what extent differences across studies are associated with differences in treatment effects. Second, from a practical perspective, relatively little is known about what common components (e.g., prerequisite skills, skill objectives) characterize effective instructional models of purchasing and money skills. Therefore, our meta-analysis synthesizes research on functional mathematics/purchasing skills instruction for individuals with developmental disabilities and analyzes the relationship between treatment effectiveness and various study features (e.g., participant characteristics, purchasing and functional math/money instructional strategy, generalization programming). Meta-analysis allows researchers to quantitatively aggregate information while considering the magnitude of treatment effects across different studies. As such, it serves to identify effective strategies and address relationships between treatment effectiveness and relevant mediating variables (e.g., Glass, 1977; Kavale, 1984; Kavale & Glass, 1984). The following research questions were addressed in this study:

* How effective is purchasing skill instruction for individuals with developmental disabilities?

* Is intervention effectiveness related to student characteristics (i.e., grade, classification label, or entry skills)?

* Does the type of instructional approach differentially influence independent purchasing skill acquisition by individuals with developmental disabilities?

* Are treatment outcomes related to instructional features (e.g., money skill adaptation, instructional setting)?

* What is the effect of the instructional approach on skill generalization?

* What is the effect of the instructional approach on skill maintenance?

METHOD

LITERATURE SEARCH PROCEDURES AND INCLUSION CRITERIA

We first conducted broad computerized searches of the literature on money or purchasing skill instruction for students with developmental disabilities using the following databases: Educational Resources Information Center (ERIC) database (1978 to 2003) and PsychLit database (1967 to 2003). Descriptors for the computerized searches included "purchasing skills," "functional math," "money management," "next dollar strategy," "community-based instruction," "disabilities," and "mental retardation."

Second, we conducted manual searches of journals that were included in articles reported in the Browder and Grasso (1999) study. Finally, we conducted an ancestral search of studies using the reference lists of identified articles as well as the two review articles. More than 350 abstracts and summaries were read during the preliminary stage of the review process. Two of the authors independently read the study abstracts to determine whether the articles met the criteria for inclusion. To judge the appropriateness of each article, we evaluated studies using five criteria. First, studies had to include an intervention to teach purchasing skills. Second, the recipients of the intervention were identified as individuals with developmental disabilities (mild, moderate, severe, profound mental retardation; autism; multiple disabilities; or dual diagnoses).

Third, single-subject or group research design studies with some form of experimental control were included in the review. Fourth, studies had to provide baseline and treatment data or pretest and posttest data that allowed for the computation of effect sizes. Fifth, only studies published in English were included in this review. We did not explore other sources of the literature (e.g., Dissertation Abstracts International) in a systematic fashion or contact active researchers in this area for unpublished studies. As such, this review may represent a potential bias toward published studies versus unpublished articles (Lipsey & Wilson, 1993); thus, conclusions based on the review should be viewed as tentative.

Many of the studies reviewed did not meet our eligibility requirements. The reason for excluding studies was primarily a failure to investigate interventions that taught money or purchasing skills. Instead, excluded studies mostly investigated strategies to (a) write checks (LaCampagne & Cipani, 1987), (b) select lower priced items using number lines (Sandknop, Schuster, Wolery, & Cross, 1992), (c) utilize automatic banking machines (McDonnell & Ferguson, 1989), or (d) understand the value and compare money amounts (Stith & Fishbein, 1996). In addition, two group design studies (i.e., Matson, 1981; Westling, Floyd, & Carr, 1990) that reported pre- and posttest scores only were not included in the review, because effect sizes for these two studies could not be calculated. In the end, a total of 28 single-subject design studies met all requirements and were selected for analysis.

CODING STUDY FEATURES

Study features that were coded included participant characteristics (i.e., grade, classification label, and entry skills) and purchasing skill instructional features (i.e., purchasing instructional strategy, money skill adaptation, type of purchase, error correction procedure, length of instruction, and instructional setting). In addition, generalization and maintenance effects were also evaluated.

PARTICIPANT CHARACTERISTICS

Grade. This variable describes the grade level of the study participants and was separated into three categories: elementary and middle school (Grades K-8), secondary (Grades 9-12), and postsecondary (adult).

Classification Label. This variable comprised three categories: (a) mild and moderate mental retardation, (b) moderate and severe mental retardation, and (c) other disabilities (i.e., autism, severe emotional disorders, dual diagnoses). Because most studies included a mixed group of participants (i.e., mild and moderate or moderate and severe), it was not possible to separate moderate disabilities from mild or severe disabilities, resulting in an overlap of disabilities in the first two categories.

Entry Skills. This variable referred to whether or not the participants in the studies began with preexisting functional mathematics skills and included three categories. Two of the three categories were defined as whether participants entered the study with money recognition skills (i.e., able to name and count dollar bills and coins) or had community experiences (but did not necessarily have the experience to handle money or recognize specific values of money). In addition, we coded a third category: participants' entry skill information was not reported.

PURCHASING SKILL INSTRUCTIONAL FEATURES

Purchasing Instructional Strategy. To evaluate the effectiveness of different instructional strategies, interventions were categorized as either modeling and/or verbal instruction or faded prompt procedures. Modeling and/or verbal instruction was defined as the instructor or videotapes/photo slides modeling the skill, providing verbal instructions, and/or role-playing the desired purchasing skill. Faded prompt procedures referred to instructional techniques that incorporated a system or schedule of fading of teacher delivered prompts to the natural discriminative stimuli, such as in a system of least prompts, most to least prompts, or constant/progressive time delay.

Money Skill Adaptation. Money transaction is one of the key components of a series of skill steps in purchasing skill instruction. To explore the relationship between instructional effectiveness and various money skill adaptations, three classes were assigned to this variable: (a) simplification, (b) next-dollar strategy, and (c) calculator use. Simplification involved providing students with a money number line or other means such as matching money to preprinted cards to assist with money payment. Another form of simplification included providing the participant with an envelope containing a predetermined amount of money needed to make a purchase. Next-dollar strategy involved counting out the next dollar to the amount to be tendered during a cash purchase transaction. The cents pile method was included in this category. It involves an additional step in the next-dollar strategy. Specifically, the student is taught to put one dollar aside for cents, count out the requested dollar amount, and combine the two piles to give to the cashier or instructor. Calculator use referred to using a calculator as a means to figure out the total cost or to make a decision as to whether or not one has enough money to make the purchase.

Type of Purchase. We coded three categories for this variable. They included (a) restaurant ordering, (b) grocery or shopping center purchases, and (c) vending machine use or money payment instruction only. Five studies involved money payment instruction only (e.g., Colyer & Collins, 1996) and were clearly distinguishable from other purchasing skill studies. For example, participants in studies involving money payment were presented with the price of an item and asked to pay the appropriate amount of money. These studies were combined with vending machine use studies, because they share common features in terms of an exclusive focus on money skill instruction.

Error Correction Procedure. Error correction procedures were coded into three categories. These included (a) verbal feedback and/or modeling, (b) physical guidance (i.e., participants repeated the correct behavior with instructor's physical guidance), and (c) no error correction procedures reported.

Setting. To examine the relationship between instructional settings and outcomes, we coded the environment in which the instruction took place as follows: (a) simulated/classroom settings, (b) community settings (in vivo instruction), and (c) simulated plus in vivo (i.e., instruction in both simulated and community settings).

Length of Treatment. Treatment duration may influence participant skill acquisition and maintenance. We coded this variable as either long (more than 15 sessions) or short (15 or fewer sessions).

Generalization. Skill generalization to novel settings, people, times, and stimulus universe are typically targeted for generalization programming (e.g., Scruggs & Mastropieri, 1994). When studies assessed and included graphed generalization data to allow for the calculation of generalization treatment effects, we coded the interventions into two categories: (a) programmed for generalization (e.g., general case instruction) and (b) not programmed for generalization.

Maintenance. To evaluate the extent to which the intervention influenced skill maintenance, we coded studies that assessed and presented maintenance data for which calculation of treatment effect was possible into two categories: maintenance probes collected 1 month or less after the termination of the intervention or probes collected beyond 1 month after the intervention.

COMPUTATION AND ANALYSIS OF TREATMENT EFFECTIVENESS

Because all studies in this meta-analysis employed a single-subject research design, a nonparametric procedure (i.e., the percentage of nonoverlapping data [PND]) was used to estimate treatment effectiveness (Scruggs, Mastropieri, & Casto, 1987). Although parametric approaches have been used to calculate effect size (e.g., the standardized mean difference), graphic display of results and a limited number of data points, especially during the baseline, present problems in using parametric procedures to quantify single-subject data and to perform reliable and valid analysis of the effect size. Therefore, PND was chosen as the effect size measure. Interpretations, based on the interpretative framework for PND articulated by Scruggs and Mastropieri (1998), are as follows: (a) > 90% is a large effect, (b) 70% to 90% is a moderate effect, (c) 50% to 70% is a low effect, and (d) < 50% is not effective.

Specifically, PND was calculated by dividing the total number of data points in the treatment phase that exceeded the highest baseline data point by the total number of data points in the treatment phase. In the case of multiple baseline studies, individual PND scores were aggregated to obtain an overall treatment effect. The dependent measure used for effect size calculation was common across all studies (i.e., the number/percentage of correct responses). Specifically, the number/percentage of correct responses for task analysis steps was measured when the intervention included a long sequence of purchasing routine. In contrast, the number/percentage of correct responses (i.e., payment) to items with different prices was measured when the training focused on the money payment skill.

After PND was calculated, results were analyzed with each coded variable as the independent variable. Kruskal-Wallis H, a nonparametric test that allows for multiple independent samples comparison, was used to test for significant differences among categories for each independent variable. In addition, because of the nonparametric nature of the PND measure and given that it is often not normally distributed, median PND was chosen as the central tendency measure of the treatment effects. The median is less likely to be skewed by "outliers" (Scruggs et al., 1987).

Most studies investigated one intervention strategy, and therefore, each study yielded one PND score for skill acquisition. However, two studies (McDonnell & Ferguson, 1988; McDonnell, Horner,& Williams 1984) compared purchasing instructional effectiveness when training was conducted in different settings (e.g., simulated or real/in vivo). As such, two and three PND scores were obtained from the McDonnell and Ferguson (1988) and McDonnell et al. studies, respectively, for each intervention strategy examined. Because these multiple interventions and their corresponding PNDs were setting related, we only included multiple PNDs from each of these comparison studies into the categorical comparison analysis when "Instructional Setting" was an independent variable. For the analysis of all other variables on skill acquisition, we aggregated the PND scores in each of these comparison studies to produce a single PND.

In addition to skill acquisition PND scores, maintenance and generalization PND scores were separately calculated and analyzed. It must be noted that one study (Sprague & Horner, 1984) compared three strategies (i.e., single case, multiple case, and general case instruction) to promote skill generalization. Therefore, three generalization PND scores were obtained from this single study when PNDs for generalization were analyzed.

INTERRATER AGREEMENT

The first author coded all studies and calculated the PND. A second rater independently coded 32% of the studies. Interrater agreement was obtained by dividing the total number of agreements by the total number of agreements plus disagreements multiplied by 100. The interrater agreement for the coding of study features was 97%, with a range of 95% to 100%. Effect size agreement was 96%, with a range of 92% to 98%. Disagreements in calculating PND were primarily due to problems in deciphering some of the graphed data points, which in turn made it difficult to judge whether or not a specific data point in intervention overlapped with baseline data.

RESULTS

OVERALL STUDY CHARACTERISTICS AND TREATMENT EFFECT

Table 1 presents the characteristics of the comparisons for the 28 single-subject design studies. Twenty-six of these studies used a multiple probe or baseline design and two studies employed a multielement alternating treatment design. The 28 studies were published from 1978 to 2000. A total of 115 participants were included in these studies. Participants' ages ranged from 6 to 74. Twenty-three studies reported participants' IQ scores with ranges of 10 to 75. In sum, the 28 single-subject studies yielded an overall moderate effect (PND = 87%; range = 59% to 100%) for purchasing skill instruction.

MODERATOR INFLUENCES ON THE EFFECT OF PURCHASING SKILL INSTRUCTION

Table 2 presents an overview of treatment effects and the number of studies or interventions in each category with regard to sample characteristics, instructional features, and other variables. Potential variables such as participant characteristics (e.g., grade, disability label, entry skills) and instructional features (e.g., instructional setting, type of instruction/adaptations, error correction procedures) were analyzed to examine their impact on purchasing skills instruction.

Participant Characteristics. The majority of the studies (n = 14, 50%) involved secondary school participants (Grades 9-12) and six studies (21%) included postsecondary students (i.e., over the age of 21). In addition, five studies (18%) included elementary school participants (i.e., Grades K-5), and three (11%) comprised middle school participants (i.e., Grades 6-8). Given the limited number of studies in the elementary and middle school categories, these two categories were combined when categorical comparisons of the 28 single-subject studies were conducted. Results of these comparisons did not indicate statistically significant differences among grade levels on the treatment. Regarding the disability category, only one study (4%) involved participants with mild disabilities. Four (14%) studies included participants with mild to moderate disabilities, and three (11%) studies consisted of participants with moderate disabilities. The majority of studies included participants with a mixture of moderate and severe disabilities (n = 12, 43%) or severe disabilities (n = 5, 18%). In contrast, only three studies (10%) involved participants with autism or severe behavior disorders. Categorical comparisons of studies analyzed revealed no statistically significant differences among disability categories in terms of purchasing skill instruction effects.

When participants' preexisting money skills were examined, differences among categories were statistically significant, [chi square](2) = 6.49, p = .04. A post hoc Mann-Whitney test indicated a statistically significant difference (p = .02) only for the first two categories. Specifically, the treatment effect for participants with money recognition skills (n = 9, PND = 94%) showed a large effect, whereas that for participants with previous community experience only (n = 10, PND = 85%) indicated a moderate effect.

Instructional Features. Moderate effects were found for the different purchasing instructional strategies, and the differences between modeling/verbal instruction (n = 9, PND = 85%) and faded prompt strategies (n = 18, PND = 89%) were not statistically significant. Further, when interventions involving time delay (n = 4, PND = 87%) were separated from those involving a system of least prompts (n = 14, PND = 91%), the differences were not statistically significant. In contrast, results for money skill adaptation (e.g., simplification, next-dollar strategy, calculator use) indicated statistically significant differences, [chi square](2) = 7.70, p [less than or equal to] .05. Further, the post hoc Mann-Whitney test revealed a statistically significant difference between simplification (n = 13, PND = 95%) that indicated a large effect and next-dollar strategy (n = 9, PND = 85%) only, p = .03, which was moderately effective.

It should be noted that results for the two studies (Gardill & Browder, 1995; Marholin, O'Toole, Touchette, Berger, & Doyle, 1979) included in the "Other" category (median PND = 82%) indicated a moderate effect. The study by Gardill and Browder taught participants to discriminate among three stimulus classes (a vending machine item, snack, and lunch) and pay the money accordingly (i.e., use 75 cents for a vending machine item, a $1 bill for a snack, and a $5 dollar bill for a lunch purchase). This was the only study (PND = 83%) that taught stimulus discrimination as a strategy to bypass the required money computation skills, which is different from the other money skill adaptation categories (e.g., simplification, next-dollar). The study by Marholin et al. also was included in the "Other" category, because it did not report the strategies used to help with the money payment part of the purchasing instruction (PND = 81%).

When instructional effectiveness across three different purchase types (i.e., restaurant ordering, grocery/shopping center purchases, and vending machine use/sole money payment instruction) was examined, results indicated statistically significant differences among the three categories, [chi square](2) = 6.20, p [less than or equal to] .05. Further, the post hoc Mann-Whitney test indicated statistically significant differences between grocery/shopping center purchasing (n = 13, PND = 94%) and vending machine use/money payment only (n = 8, PND = 83%), p = .04. Post hoc analysis also indicated that when restaurant ordering and grocery/shopping center purchasing were combined, a statistically significant difference was found between this combined category and the vending machine use/sole money payment category, [chi square](1) = 4.91, p = .03. No statistically significant differences were found between restaurant ordering (n = 6, PND = 91%) and grocery/shopping center purchasing. Both types of purchases were seen to be highly effective.

Categorical comparisons indicated a statistically significant difference for error correction procedures, [chi square](2)= 11.07, p = .00. Further, post hoc analysis showed a statistically significant difference between error correction involving verbal instruction/modeling that demonstrated a moderate treatment effect (n = 10, PND = 84%) and physical guidance, which was highly effective (n = 15, PND = 92%), p = .04. Regarding intervention duration, even though long treatments (i.e., more than 15 sessions, n = 15, PND = 90%) were highly effective when compared to short treatments (i.e., 15 sessions or fewer, n = 13, PND = 86%) that showed a moderate effect, the differences between these two categories were not statistically significant. However, analyses for instructional settings showed a statistically significant difference between training conducted in simulated plus in vivo settings (n = 11, PND = 94%) and those in simulated settings only (n = 11, PND = 85 %), p = .03.

Generalization. A total of 18 studies that collected and graphed generalization data resulted in 21 PND scores, with a moderate generalization effect (PND = 86%; range = 0%-100%). Results indicated that interventions that programmed for generalization (n = 10, PND = 95%) were highly effective when compared to those that did not program for generalization (n = 11, PND = 83%), which revealed a moderate effect. However, the difference between the two categories was not statistically significant given the limited generalization database.

Maintenance. A total of 19 studies collected and graphed maintenance data. Overall, results indicated high maintenance effects (PND = 100%; range 67%-100%) for these studies. When maintenance effects were analyzed in terms of the extent to which learned skills were maintained, results indicated no statistically significant differences between studies that conducted maintenance probes within 1 month after the termination of the intervention (PND = 100%) and studies that conducted probes beyond 1 month (PND = 100%).

DISCUSSION

HOW EFFECTIVE IS PURCHASING SKILL INSTRUCTION FOR INDIVIDUALS WITH DEVELOPMENTAL DISABILITIES?

In general, results of this meta-analysis suggest that purchasing skill instruction is moderately effective (PND = 87%; range = 59% to 100%) in teaching individuals with developmental disabilities to make independent purchases. Based on the studies that provided maintenance and generalization data, results indicated that participants were able to maintain the learned skills (median PND = 100%) for at least 1 week to a maximum of 5 months (e.g., Storey, Bates, & Hanson, 1984) and generalize to new contexts (median PND = 86%).

IS INTERVENTION EFFECTIVENESS RELATED TO STUDENT CHARACTERISTICS?

Participants' grade levels and disability categories did not have an influence on purchasing/functional math skills instruction. However, it must be noted that we did not separate the category of moderate disabilities from mild or severe disabilities. As such, the first two categories of disabilities used in this meta-analysis were not mutually exclusive, and this may possibly explain the statistically nonsignificant results. In addition, the third category (i.e., autism) included only three cases that may have contributed to the low statistical power of finding differences.

In contrast, participants' relevant entry skills were related to purchasing skill effectiveness. Specifically, those studies that involved participants who were able to recognize and count coins or dollar bills yielded greater treatment effects than those that involved participants who had community experience only or lacked experience or prerequisite skill knowledge. This finding suggests that money skills may be a key component in the purchasing routine, because participants who had these prerequisite skills fared better than those without them. Although several purchasing skill interventions adopted some kind of a modification (e.g., prepared money envelopes, money number line, next-dollar strategy) to bypass money skills, participants with prerequisite money skills responded better to purchasing instruction than those without these skills. Our results are consistent with recommendations from a previous review by Browder and Grasso (1999), which not only indicated that providing students with opportunities to practice money skills both in the community and classroom is important, but also that students with prerequisite skills acquire purchasing skills more efficiently.

WHICH TYPE OF INSTRUCTIONAL APPROACH IS MOST EFFECTIVE WITH REGARD TO INDEPENDENT PURCHASING SKILL ACQUISITION BY INDIVIDUALS WITH DEVELOPMENTAL DISABILITIES?

Results of our study do not support the findings in the literature about the relative importance of prompting and fading strategies when compared to other instructional procedures (e.g., Browder & Grasso, 1999; Morse et al., 1996). Both instructional strategies of modeling/verbal instruction and the faded prompt procedure yielded similar PND scores. It is important to note that both categories included a variety of strategies. The first category (n = 9) included not only preresponse strategies (e.g., modeling, verbal instruction, role-playing, videotape presentation), but also postresponse strategies (e.g., verbal feedback). Because of the limited number of PNDs in this category, further analyses were not conducted. In contrast, the second category included least-to-most prompting or most-to-least prompting strategies as well as time delay.

Purchasing skills in the identified studies ranged from teaching money skills only (e.g., cash register payment) to vending machine use, restaurant ordering, and grocery/shopping center purchases. These skills require quite different purchasing activities that involve a different number of task steps. As such, it might be the case that different strategies are beneficial for teaching different types of skill chains. For example, whereas preresponse modeling might be appropriate for shorter chained skills, the system of least prompts might be necessary for skills that involve a long list of steps. Modeling and role play may be critical for training in a simulated setting, but may not be appropriate in a real setting. Therefore, it is important to analyze the nature of the skill to be taught and choose an instructional strategy that does not stigmatize individuals with disabilities. At the same time, it is important to consider both the effectiveness and efficiency of the strategy.

ARE TREATMENT OUTCOMES RELATED TO INSTRUCTIONAL FEATURES?

Results of this meta-analysis revealed that different types of purchasing instruction yielded different treatment effects. In general, grocery/ department store shopping and restaurant ordering instruction yielded higher PND scores than those for vending machine use or money payment instruction only. It should be noted that grocery/department store shopping as well as restaurant ordering typically involved numerous steps other than money payment. For example, the task analysis steps for shopping in a grocery store may include as many as 32 steps (e.g., walks to store entrance door, goes through the door, walks in the store, ... exits store). In such cases, when the participant learned any of these steps, the dependent measure (i.e., number of steps correct) in the treatment phase would show improvement over the baseline. In other words, the improvement in the dependent measure may not reflect money skill learning, which is only one component among a long list of task analysis steps in the entire purchasing routine.

Regarding money skill adaptation, results indicated that when purchasing instructional strategies involved simplification strategies (e.g., prepared money envelopes) to bypass money skills (e.g., Smeets, 1978), the treatment yielded higher PND scores than those that provided less support for money skill instruction, such as the use of the next-dollar strategy, which skips only the cents counting step. This finding regarding the importance of money skill adaptation is supported in the literature, which indicates that simplification strategies may reduce the overall academic demands of money use (Browder & Grasso, 1999; Morse et al., 1996). However, with respect to calculator use, this category failed to show any differentially statistically significant treatment effects when compared to the other categories, despite the large PND score of 91% for this category. This finding may be explained by the low number of studies (n = 4) involving calculator use. It must be noted that participants in these studies were taught to use the calculator either to figure out the exact purchasing amount or to make sure that the purchases did not go over the budget limit.

Money skills play a major role in the whole purchasing process or are the sole focus in studies on vending machine use or payment skill instruction only. In these studies, when the participant missed the money transaction step, the PND score, which is the measure of the treatment effect, was dramatically influenced. In fact, the PND score in these studies is a more direct measure of money skill as compared to studies that teach a considerable number of task steps other than money skills in the purchasing process. In summary, the results suggest relatively lower treatment effects when the task or training focused exclusively on money skills. This finding indicates the need for additional work in this area and supports previous research recommendations about expanding instruction to include all skills associated with money management (Browder & Grasso, 1999; Morse et al., 1996).

Results of this review also suggest that treatments that involved a terminal level of error correction procedure (i.e., physical guidance) yielded higher PND scores than those involving only verbal instruction or modeling. Physical guidance to correct errors ensured opportunities for learners to repeat the correct behavior and therefore facilitated skill acquisition. Verbal instructions or modeling alone may not be enough to shape appropriate purchasing behaviors. It is critical that instructional planning carefully address the level of error correction needed for the student to learn the appropriate response.

Instructional setting is another variable to consider when providing purchasing skill training, especially with regard to cost effectiveness and efficiency. Will students learn purchasing skills in a simulated setting (e.g., classroom) or does the skill have to be trained in the real setting? Results of this meta-analysis suggest that combining simulated and in vivo training yielded better results. It may be the case that certain prerequisite and critical skills (e.g., functional math skill to deal with money transaction) are better trained in a simulated setting with a better control of the learning environment than in a real setting. For example, conducting mass trials of a single skill (e.g., money payment) may not be feasible in a real setting. As such, it is important to balance instruction by providing opportunities for learning in both the classroom and community. Beginning a lesson with classroom money skill instruction may better prepare students for the expectations of the natural setting.

Finally, the number of training sessions did not appear to be related to purchasing skill instructional effects. A plausible explanation for this finding is that purchasing interventions identified in these studies varied to a large extent in terms of the complexity of target skills taught. Purchase skills taught ranged from simple one-item purchase with or without a bypass money skill adaptation (e.g., predetermined dollar amount) to more complex multiple item purchasing with or without money skill adaptation. As such, sessions needed to reach training criterion may vary dramatically as a function of the target skills.

WHAT IS THE EFFECT OF THE INSTRUCTIONAL APPROACH ON SKILL GENERALIZATION?

Based on the results of 18 studies that reported generalization data, a moderate generalization effect (PND = 86%) was found. Of the 18 studies, about half of the interventions (n = 10) programmed for generalization yielded a large treatment effect (PND = 95%). This finding indicated that participants readily generalized the learned purchasing skills to novel settings, supporting previous research recommendations of programming for generalization throughout instruction (Browder & Grasso, 1999; Morse et al., 1996). However, the results of the meta-analysis failed to show significantly different generalization effects between interventions that programmed for generalization and those that did not program for generalization. It should be noted that interventions that programmed for generalization varied in the studies reviewed. They included stimulus generalization, in which training involved presenting various purchasing items' price range and verbal statement of the price (n = 6, PND = 89%) and setting generalization, in which training involved various sites where the purchasing skill would be applicable (n = 4, PND = 98%). Although interventions that programmed for generalization, especially those for setting generalization, yielded a large treatment effect (PND = 98%) and interventions that did not program for generalization produced a moderate treatment effect (n = 11, PND = 83%), nonparametric analyses failed to show statistical significance. It is plausible that the limited number of cases in each subcategory may have masked treatment effects. It must be noted that 5 of the 10 studies that did not provide graphed data needed to calculate generalization PNDs noted partial skill generalization (see Table 1). Interestingly, all five studies reported successful applications of the stimulus generalization strategies, which seem to add further to the importance of generalized instructional strategies.

WHAT IS THE EFFECT OF THE INSTRUCTIONAL APPROACH ON SKILL MAINTENANCE OVER TIME?

About 61% of the studies (n = 19) reported maintenance data, and findings indicated high maintenance effects (PND = 100%). In addition, the results indicated that maintenance effects did not decrease with the increase of elapsed time. Specifically, maintenance effects acquired within a 1-month period were not significantly different from those obtained beyond 1-month follow-up (up to a maximum of 5 months). Again, this result should be interpreted with caution given the limited maintenance data.

Although results of the meta-analysis indicated that purchasing and money skill instruction revealed moderate-to-high effects for students with developmental disabilities, the present synthesis is limited in several ways and should be interpreted cautiously. First, the PND measure may not be sensitive in evaluating the magnitude of treatment effects, because it only counts whether or not the treatment data points overlap with the baseline data points. For a single data point, PND will only consider it as either a hit or miss (i.e., overlap or not overlap) rather than how much it hit or missed. In addition, the PND does not address changes in trend from baseline to treatment performance. Further, the PND measure can result in a ceiling effect, because the largest possible treatment effect defined by PND is 100%. Therefore, this technique might not have sufficient power to find all potential differences when categorical comparisons are conducted. Second, because of the limited database, only main effects of each variable (e.g., grade, purchasing instructional strategies) were analyzed for categorical comparisons. Further within class analysis for possible interactions among variables were not conducted because of the limited number of cases.

In summary, the effects of purchasing skill instruction for students with developmental disabilities are encouraging. On the basis of this review, we draw some tentative conclusions about how to promote purchasing skills for individuals with developmental disabilities and offer some specific recommendations and directions for future study based on the key findings of our review,

IMPLICATIONS FOR PRACTICE

Our analysis of the studies reviewed indicates that although modeling/verbal instruction and prompting procedures are equally effective in enhancing purchasing skill performance, a strong foundation in functional mathematical skills (e.g., coin recognition, counting) is required for enhancing competent performance by students with developmental disabilities (Morse et al., 1996; Schloss, Kobza, & Alper, 1997). This would require having the necessary prerequisite money recognition skills to effectively respond to purchasing instruction. Money skills appear to be a difficult part of purchasing routines for students with developmental disabilities given the demands of basic academic skills. Therefore, additional instruction in this area is needed.

Second, it would be beneficial to teach or apply money skill adaptations to bypass the money skill in purchasing routines when these prerequisite skills are lacking. Our review suggests the contribution of simplification strategies (e.g., prepared money envelopes) over the next-dollar strategy on purchasing skill performance for students with developmental disabilities.

Third, our review suggests that tasks that involved relatively more independent money handling (e.g., vending machine use) were seen to be difficult for participants with disabilities, indicating the need for additional work to identify effective ways to increase the magnitude of purchasing skill effects for a range of purchasing tasks.

Fourth, there also appears to be a need for providing both simulated and in vivo instruction. Simulated practice on purchasing skill routine and prerequisites skills in the classroom prior to instruction in the natural setting (e.g., community) may contribute to both the effectiveness and efficiency of the intervention.

Fifth, our results suggest that physical guidance, as a corrective feedback procedure, is relatively more effective than either verbal instruction or modeling. This indicates the relevance of actual guidance not only for reducing errors, but also for providing a coherent illustration of how to complete the task.

RECOMMENDATIONS FOR FUTURE RESEARCH

Although the majority of the research on purchasing skills has been conducted with secondary school students, relatively few studies involved elementary and middle school students, indicating the need for additional research with this population. Undoubtedly, money skill acquisition for secondary students who are making the transition to the real world is critical. In fact, it is an essential community living goal and commonly included as one of the IEP transition goals for students with developmental disabilities. However, the need for early functional math skills (e.g., purchasing, money) instruction in the elementary grades is necessary for increased functional competence in later years.

Second, continued research is required to address the effects of independent community functioning skill instruction for subgroups of stu dents with developmental disabilities. Clearly defining the population (mild, moderate, severe MR) is seen as critical to interpreting study findings. Many of the studies in this review included a mixture of disability categories. Therefore, further investigation of the effects of purchasing skill instruction for subgroups of students with disabilities, who differ in functional competence and verbal strengths, is needed.

Third, additional research is needed to systematically examine the separate effects of various instructional procedures (e.g., modeling, verbal instruction, role-playing, videotape presentation, verbal feedback, least-to-most prompting, most-to-least prompting, time delay) on purchasing skill performance. Fourth, continued research is required to assess generalization and maintenance of the skills given the limited database. The practice of teaching and assessing on an ongoing basis for maintenance and generalization is important. Presenting opportunities for students to apply the learned skills in new situations and contexts is especially important for students with developmental disabilities.

Finally, a direction for future study relates to access to the general educational curricula for students with moderate and severe disabilities. Although the 1997 reauthorization of the Individuals with Disabilities Education Act (IDEA, 1999) with regard to access to the general curriculum for students with developmental disabilities has generated some confusion, researchers in severe disabilities are unequivocal about the need for continued focus on functional life skills (community and money management skills) for these students (Browder et al., 2003). Intensifying instruction on functional life skills (e.g., money management) that builds on basic academic skills, for example, represents one means of accessing the general education curriculum.

REFERENCES

* -- References marked with an asterisk indicate studies included in the meta-analysis.

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* Browder, D. M., & Snell, M. E., & Wildonger, B. (1988). Simulation and community-based instruction of vending machines with time delay. Education and Training in Mental Retardation, 23, 175-185.

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* Colyer, S. P., & Collins, B. C. (1996). Using natural cues within prompt levels to teach the next dollar strategy to students with disabilities. Journal of Special Education, 30, 305-318.

* Denny, P. J., & Test, D. W. (1995). Using the One-More-Than technique to teach money counting to individuals with moderate mental retardation: A systematic replication. Education and Treatment of Children, 18, 422-432.

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* Frank, A. R., & Wacker, D. P. (1986). Analysis of a visual prompting procedure on acquisition and generalization of coin skills by mentally retarded children. American Journal of Mental Deficiency, 90, 468-472.

* Fredrick-Dugan, A., Test, D. W, & Varn, L. (1991). Acquisition and generalization of purchasing skills using a calculator by students who are mentally retarded. Education and Training in Mental Retardation, 26, 381-387.

* Gardill, C. M., & Browder, D. M. (1995). Teaching stimulus classes to encourage independent purchasing by students with severe behavior disorders. Education and Training in Mental Retardation, 30, 254-264.

* Gaule, K., Nietupski, J., & Certo, N. (I985). Teaching supermarket shopping skills using an adaptive shopping list. Education and Training of the Mentally Retarded, 20, 53-59.

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* Haring, T. G., Breen, C. G., Weiner, J., Kennedy, C. H., & Bednersh, F. (1995). Using videotape modeling to facilitate generalized purchasing skills. Journal of Behavioral Education, 5, 29-53.

* Haring, T. G., Kennedy, C. H., Adams, M. J., & Pitts-Conway, V. (1987). Teaching generalization of purchasing skills across community settings to autistic youth using videodisc modeling. Journal of Applied Behavior Analysis, 20, 89-96.

Hughes, C., Eisenman, L. T., Hwang, B., Kim, J. H., Killian, D. J., & Scott, S. V. (1997). Transition from secondary special education to adult life: A review and analysis of empirical measures. Education and Training in Mental Retardation and Developmental Disabilities, 3, 85-104.

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LaCampagne, J., & Cipani, E. (1987). Training adults with mental retardation to pay bills. Mental Retardation, 25, 293-303.

Lehmann, J. P., Bassett, D. S., Sands, D. J., Spencer, K., & Gliner, J. A. (1999). Research translated into practices for increasing student involvement in transition related activities. Career Development for Exceptional Individuals, 22, 3-18.

Lipsey, M. W., & Wilson, D. B. (1993). The efficacy of psychological, educational, and behavioral treatment. American Psychologist, 48, 1181-1209.

* Marholin, D., O'Toole, K. M., Touchette, P. E., Berger, P. L., & Doyle, D. A. (1979). "I'll have a Big Mac, large fries, large coke, and apple pie, ... or teaching adaptive community skills. Behavior Therapy, 10, 236-248.

Matson, J. L. (1981). Use of independence training to teach shopping skills to mildly mentally retarded adults. American Journal on Mental Deficiency, 86, 178-183.

* Matson, J. L., & Long, S. (1986). Teaching computation/shopping skills to mentally retarded adults. American Journal of Mental Deficiency, 91, 98-101.

* McDonnell, J. (1987). The effects of time delay and increasing prompt hierarchy strategies on the acquisition of purchasing skills by students with severe handicaps. The Journal of the Association for Persons with Severe Handicaps, 12, 227-236.

* McDonnell, J., & Ferguson, B. (1988). A comparison of general case in vivo and general case simulation plus in vivo training. The Journal of the Association for Persons with Severe Handicaps, 13, 116-124.

* McDonnell, J., & Laughlin, B. (1989). A comparison of backward and concurrent chaining strategies in teaching community skills. Education and Training in Mental Retardation, 24, 230-238.

McDonnell, J. J., & Ferguson, B. (1989). A comparison of time delay and decreasing prompt hierarchy strategies in teaching banking skills to students with moderate handicaps. Journal of Applied Behavior Analysis, 22, 85-91.

* McDonnell, J. J., Horner, R. H., & Williams, J. A. (1984). Comparison of three strategies for teaching generalized grocery purchasing to high school students with severe handicaps. The Journal of the Association for Persons with Severe Handicaps, 9, 123-133.

Moon, M. S., & Inge, K. (2000). Vocational preparation and transition. In F. Brown & M. E., Snell (Eds.), Instruction of students with severe disabilities (pp. 591-626). Upper Saddle River, NJ: Merrill/Prentice-Hall..

* Morse, T. E., & Schuster, J. W. (2000). Teaching elementary students with moderate intellectual disabilities how to shop for groceries. Exceptional Children, 66, 273-288.

Morse, T. E., Schuster, J. W., & Sandknop, P. A. (1996). Grocery shopping skills for persons with moderate to profound intellectual disabilities: A review of the literature. Education and Treatment of Children, 19, 487-517.

* Nietupski, J., Clancy, P., & Christiansen, C. (1984). Acquisition, maintenance, and generalization of vending machine skills by moderately handicapped students. Education and Training in Mental Retardation, 3, 91-96.

* Nietupski, J., Welch, J., & Wacker, D. (1983). Acquisition, maintenance, and transfer of grocery item purchasing skills by moderately and severely handicapped students. Education and Training in Mental Retardation, 18, 279-286.

Patton, J. P., Cronin, M. E., & Jairrels, V. (1997). Curricular implications of transition: Life skills instruction as an integral part of transition education. Remedial and Special Education, 18, 294-306.

Revell, G., Kregel, J., Wehman, P., & Bond, G. R. (2000). Cost effectiveness of supported employment programs: What we need to do to improve outcomes. Journal of Vocational Rehabilitation, 14, 173-178.

Rusch, F. R., Szymanski, E. M., & Chadsey-Rusch, J. (1992). The emerging field of transition services. In F. R. Rusch, L. Destefano, J. Chadsey Rusch, L. A. Phelps, & E. Szymanski (Eds.), Transition from school to adult life: Models, linkages, and policy (pp. 5-16). Sycamore, IL: Sycamore.

Sandknop, P. A., Schuster, J. W., Wolery, M., & Cross, D. P. (1992). The use of an adaptive device to teach students with moderate mental retardation to select lower priced grocery items. Education and Training in Mental Retardation, 27, 219-229.

* Schlein, S. J., Certo, N. J., & Muccino, A. (1984). Acquisition of leisure skills by a severely handicapped adolescents: A data-based instructional program. Education and Training of the Mentally Retarded, 19, 297-305.

* Schloss, P. J., Kobza, S. A., & Alper, S. (1997). The use of peer tutoring for the acquisition of functional math skills among students with moderate retardation. Education and Treatment of Children, 20, 189-208.

Scruggs, T. E., & Mastropieri, M. A. (1994). The effectiveness of generalization training: A quantitative synthesis of single-subject research. In T. E. Scruggs & M. A. Mastropieri (Eds.), Advances in learning and behavioral disabilities (Vol. 8, pp. 259-280). Greenwich, CT: JAI Press.

Scruggs, T. E., & Mastropieri, M. A. (1998). Summarizing single-subject research: Issues and applications. Behavior Modification, 22, 221-242.

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* Smeets, P. M. (1978). Teaching retarded adults monetary skills using an experimental calculator. Behavioral Engineering, 5, 51-59.

* Sprague, J. R., & Horner, R. H. (1984). The effects of single instance, multiple instance, and general case training on generalized vending machine use by moderately and severely handicapped students. Journal of Applied Behavior Analysis, 17, 273-278.

Stith, L. E., & Fishbein, H. D. (1996). Basic money-counting skills of children with mental retardation. Research in Developmental Disabilities, 17(3), 185-201.

* Storey, K., Bates, P., & Hanson, H. B. (1984). Acquisition and generalization of coffee purchasing skills by adults with severe disabilities. Journal of the Association far Persons with Severe Disabilities, 9, 178-185.

* Test, D. W., Howell, A., Burkhart K., & Beroth, T. (1993). The one-more-than technique as a strategy for counting money for individuals with moderate mental retardation. Education and Training in Mental Retardation, 1, 232-241.

* Van den Pol, R. A., Iwata, B. A., Ivancic, M. T., Page, T. J., Neef, N. A., & Whitley, F. P. (1981). Teaching the handicapped to eat in public places: Acquisition, generalization, and maintenance of restaurant skills. Journal of Applied Behavior Analysis, 14, 61-70.

* Westling, D. L., Floyd, J., & Carr, D. (1990). Effects of single setting versus multiple setting training on learning to shop in a department store. American Journal on Mental Retardation, 94, 616-624.

* Wissick, C. A., Lloyd, C., & Kinzie, M. B. (1992). The effects of community training using a videodisk-based simulation. The Journal of Special Education Technology, 11, 207-222.

Zhang, D., & Stecker, P. M. (2001). Student involvement in transition planning: Are we there yet? Education and Training in Mental Retardation and Developmental Disabilities, 36, 293-303.

YAN PING XIN

Purdue University

EDWARD GRASSO

Colonial Intermediate Unit 20

CAROLINE M. DIPIPI-HOY

Easton Area High School

ASHA JITENDRA

Lehigh University

YAN PING XIN (CEC Chapater #70), Assistant Professor of Special Education, Purdue University, West Lafayette, Indiana. EDWARD GRASSO, Supervisor of Special Education, Colonial Intermediate Unit 20, Easton, Pennsylvania. CAROLINE M. DIPIPI-HOY (CEC Chapater #905), Easton Area High School, Bethlehem, Pennsylvania. ASHA JITENDRA (CEC Chapater #905), Professor of Special Education, Lehigh University, Bethlehem, Pennsylvania.

Send correspondence to Yan Ping Xin, Purdue University, Beering Hall of Liberal Arts and Education, Department of Educational Studies, 100 North University Street, West Lafayette, IN 47907-2098 (e-mail: yxin@purdue.edu)

Manuscript received October 2003; accepted January 2004.
TABLE 1
Studies Included in the Purchasing Instruction Review

                  Participant            Entry Skill; Skill
Author            Description            Objective

Aeschleman &      4 secondary            Visited grocery
Schladenhauffen   students with          stores as part of
(1984)            severe                 CBI plan(s);
                  disabilities; CA =     purchase groceries
                  17-18; IQ = 27-35      for a brown bag
                                         lunch.

Alcantara         3 elementary           Prior informal
(1994)            students with          training in grocery
                  moderate MR;           shopping, but
                  CA = 8-9; IQ =         shopping skills not
                  NA.                    yet acquired;
                                         purchase a grocery
                                         item.

Browder, Snell,   4 elementary           Able to match
& Wildonger       school students        coins; select coins
(1988)            with moderate to       for vending
                  severe MR; CA          machine
                  = 9-12; IQ = 31-54     purchasing.

Colyer &          4 secondary            Able to distinguish
Collins           students with          among one, five,
(1996)            mild/moderate          and ten-dollar bills
                  MR; CA = 12-15;        and count to 15; use
                  IQ = 40-60.            next-dollar strategy
                                         to make payment
                                         when presented with
                                         the price.

Denny & Test      3 secondary            With community
(1995)            students with          experience but no
                  mild/moderate          dollar bill
                  MR; CA = 17;           recognition skills;
                  IQ = 39-72.            use next-dollar
                                         strategy with one,
                                         five, and ten-dollar
                                         bills to make
                                         purchases.

Frank &           4 elementary           NA; count coins
Wacker (1986)     school students        using a number
                  with mild MR;          line to make
                  CA = 11-13; IQ =       purchases.
                  58-70.

Fredrick-         2 secondary            Able to recognize
Dugan, Test, &    students with          and give correct
Vam (1991)        moderate to            amounts for all
                  severe MR;             coins and paper
                  CA = 18-20; IQ         denominations; use
                  = 36-40.               a calculator to make
                                         purchases.

Gardill &         3 middle school        Limited monetary or
Browder           students with          math skills, failed to
(1995)            severe behavior        learn next-dollar
                  disorders; CA =        strategy;
                  12-13; IQ = 45-57.     discriminate
                                         between 3 stimulus
                                         classes (a vending
                                         machine item,
                                         snack, and lunch) to
                                         encourage
                                         independent
                                         purchase.

Gaule,            3 secondary            Able to name coins,
Nietupski, &      students with          their values, and
Certo (1985)      moderate to            count to 15; use an
                  severe MR; CA          adaptive shopping
                  = 17-20; IQ = 33-36.   aid to purchase
                                         grocery items.

Haring, Breen,    6 middle school        NA; acquire and
Weiner,           students with          generalize
Kennedy, &        autism and             independent
Bednersh          severe MR; CA          purchasing
(1995)            = 10-16; IQ =          responses.
                  NA.

Haring,           3 secondary            NA; generalize
Kennedy,          students with          purchasing skills
Adams, &          autism; CA = 20;       across community
Pitts-Conway,     IQ = NA.               settings.
(1987)

Marholin,         4 adults with          NA; purchase an
O'Toole,          moderate/severe        item and pay for a
Touchette,        MR; CA = 39-63;        meal.
Berger, &         IQ = 25-53.
Doyle (1979)

Matson &          3 adults with          Able to perform
Long (1986)       mild/moderate          self-help skills,
                  MR; CA = 32-53;        count numbers to
                  IQ = 53-69.            100, count money
                                         denominations,
                                         read food prices,
                                         and read sight
                                         words; use a
                                         calculator to make
                                         purchases.

McDonnell         4 secondary students   NA; purchase snack
(1987)            with severe MR; CA     food by handing
                  = 16-18; IQ = 10-34.   cashier a dollar bill
                                         for items worth less
                                         than a dollar.

McDonnell &       6 middle school        Able to identify #'s
Ferguson          students with          0-9 and rote count
(1988)            moderate and           to 10; make
                  severe MR; mean        generalized
                  CA = 12; IQ = 43-54.   purchases at
                                         restaurants.

McDonnell,        4 secondary            Able to rote count
Homer, &          students with          from 1-10 and
Williams,         moderate and           recognize #'s from
(1984)            severe MR; CA =        0-9; make
                  16-19; IQ = 36-50.     generalized
                                         purchases in
                                         community grocery
                                         stores.

McDonnell &       4 adults with          NA; purchase two
Laughlin          severe MR; CA =        snack food items at
(1989)            26-43;                 a supermarket and a
                  IQ = 23-30.            fast food restaurant.

Morse &           10 elementary          NA; make grocery
Schuster          students with          purchases.
(2000)            moderate MR; CA
                  = 6-12; IQ = 40-57.

Nietupski,        4 elementary           Able to discriminate
Clancy, &         students with          and name coins,
Christiansen      moderate MR; CA        affix values, and
(1984)            = 7-10; IQ = 44-51.    label numbers to
                                         100; use a picture-
                                         prompt prosthetic to
                                         make vending
                                         machine purchases.

Nietupski,        4 secondary            Able to recognize
Welch, &          students with          coin names and
Wacker,           moderate and           values, count
(1983)            severe MR; CA =        pennies to 17, and
                  14-20; IQ = 32-57.     name #'s 0-9; use a
                                         pocket calculator to
                                         purchase grocery
                                         items.

Schlein,          1 secondary            No number
Certo, &          student with severe    recognition skills;
Muccino,          MR; CA = 16;           pay for the bowling
(1984)            IQ = 32.               game, purchase a
                                         drink and a snack
                                         from vending
                                         machine.

Schloss,          6 secondary school     Recognize numbers
Kobza, &          students with          from 0-5 at a
Alper (1997)      moderate to severe     minimum; use peer
                  MR; CA =14-17;         tutoring to teach the
                  IQ = 32-52.            next-dollar strategy.

Smeets (1978)     3 adults with          NA; pay exact
                  moderate and           amounts of money
                  severe MR; CA =        using a calculator.
                  20-29; IQ = 35-46.

Sprague, &        6 secondary            NA; use prosthetic
Horner (1984)     students with          card to make
                  moderate and           purchases from a
                  severe MR; CA =        vending machine.
                  15-19; IQ = NA.

Storey, Bates,    6 adults with          NA; purchase coffee
& Hanson          severe MR; CA =        by handing a dollar
(1984)            25-74; IQ = 10-59.     bill to the cashier
                                         and waiting for
                                         change.

Test, Howell,     2 adults (in Expt.     Able to count
Burkhart, &       1) and 3 high          consecutively to 20
Beroth (1993)     school students (in    with one-to-one
                  Expt. 2) with          correspondence;
                  moderate and           purchase a snack
                  severe MR; CA =        using the one-more-
                  16-24; IQ = 31-46.     than strategy.

Van den Pol,      3 secondary            NA; purchase at a
Iwata,            students with          restaurant by
Ivancic, Page,    moderate and mild      rounding up the
Neef, &           MR; CA = 17-20;        meal cost to the
Whitley           IQ = 46-75.            nearest dollar.
(1981)

Wissick,          3 secondary            Participants
Lloyd, &          students with          shopped at grocery
Kinzie (1992)     moderate to severe     store as part of CBI
                  MR; CA = 12-17;        plan; purchase
                  IQ = NA.               snack items in
                                         convenience stores.

                  Adaptations,        Study Design
                  Aids, Task          & Procedural
Author            Simplification      Fidelity

Aeschleman &      Picture prompt      A multiple
Schladenhauffen   for item            probe across
(1984)            selection and       participants;
                  next-dollar         procedural
                  strategy.           fidelity: No.

Alcantara         Grocery item        Multiple
(1994)            photographs,        baseline
                  predetermined       across
                  dollar amount.      settings;
                                      procedural
                                      fidelity: Yes.

Browder, Snell,   Coin card for       Multiple
& Wildonger       matching.           probe across
(1988)                                subject pairs;
                                      procedural
                                      fidelity: Yes.

Colyer &          Next-dollar         Multiple
Collins           strategy.           probe across
(1996)                                participants;
                                      procedural
                                      fidelity: Yes.

Denny & Test      One-More-Than       Multiple
(1995)            technique           baseline
                  with the            across
                  cents-pile          students;
                  modification.       procedural
                                      fidelity: Yes.

Frank &           Coin matching       Multiple
Wacker (1986)     cards and           baseline
                  number line.        across
                                      participants;
                                      procedural
                                      fidelity: No.

Fredrick-         Picture prompt      Multiple
Dugan, Test, &    money card          probe across
Vam (1991)        and pocket          participants;
                  calculator.         procedural
                                      fidelity: No.

Gardill &         Photos of           Multiple
Browder           money               baseline
(1995)            amounts and         across
                  the purchase        participants;
                  item.               procedural
                                      fidelity: Yes.

Gaule,            Adaptive            Modified
Nietupski, &      shopping aid        multiple
Certo (1985)      with money          probe across
                  line.               skill cluster;
                                      procedural
                                      fidelity: No.

Haring, Breen,    Multiple probe      Provided with
Weiner,           across settings;    prespecified
Kennedy, &        procedural          amount of
Bednersh          fidelity: No.       money to
(1995)                                make a
                                      purchase.

Haring,           One dollar          Multiple
Kennedy,          more payment        baseline across
Adams, &          strategy.           participants;
Pitts-Conway,                         procedural
(1987)                                fidelity: No

Marholin,         NA                  Multiple
O'Toole,                              baseline across
Touchette,                            participants;
Berger, &                             procedural
Doyle (1979)                          fidelity: No.

Matson &          Pocket calculator   Multiple
Long (1986)       and paying an       baseline
                  amount of money     across
                  greater than        settings;
                  required.           procedural
                                      fidelity: No.

McDonnell         Shopping cards.     Multielement,
(1987)                                alternating
                                      treatment
                                      within
                                      participants;
                                      procedural
                                      fidelity: Yes.

McDonnell &       Next-dollar         Multiple-
Ferguson          strategy.           baseline
(1988)                                across
                                      participants;
                                      procedural
                                      fidelity: No.

McDonnell,        Next-dollar         Multiple
Homer, &          strategy, slides,   probes across
Williams,         and flashcards.     participants;
(1984)                                procedural
                                      fidelity: No.

McDonnell &       Predetermined       Multielement,
Laughlin          dollar amount       alternating
(1989)            (two $1 bills).     treatment
                                      across skills;
                                      Procedural
                                      fidelity: No.

Morse &           Predetermined       Multiple
Schuster          amount of           probe across
(2000)            money within        participants;
                  envelope and        procedural
                  pictorial           fidelity: No.
                  storyboard.

Nietupski,        Coin card.          Multiple
Clancy, &                             probe across 3
Christiansen                          vending
(1984)                                machines and
                                      across
                                      participants;
                                      procedural
                                      fidelity: No.

Nietupski,        Pocket              Multiple
Welch, &          calculator and      probe across
Wacker,           picture prompt      participants;
(1983)            money card for      procedural
                  calculating         fidelity: No.
                  sales tax.

Schlein,          Picture card        Multiple
Certo, &          and                 baseline
Muccino,          predetermined       across skills;
(1984)            money amount.       procedural
                                      fidelity: No.

Schloss,          Next-dollar         Multiple
Kobza, &          strategy and        baseline
Alper (1997)      money cards.        across subject
                                      pairs with
                                      changing
                                      criteria;
                                      procedural
                                      fidelity: Yes.

Smeets (1978)     Pocket              Multiple
                  calculator.         baseline
                                      across
                                      participants;
                                      procedural
                                      fidelity: Yes.

Sprague, &        Prosthetic card.    Multiple-
Horner (1984)                         baseline
                                      across
                                      students;
                                      procedural
                                      fidelity: Yes

Storey, Bates,    Provided with       Multiple-
& Hanson          $1 bill for         probe across
(1984)            payment.            participants.;
                                      procedural fi
                                      delity: No.

Test, Howell,     One-more-than       Multiple
Burkhart, &       strategy with       baseline
Beroth (1993)     the cents-pile      across
                  modification.       behaviors and
                                      across
                                      participants;
                                      procedural
                                      fidelity: Yes.

Van den Pol,      Round up to         Multiple
Iwata,            next dollar, use    baseline
Ivancic, Page,    fingers to          across
Neef, &           determine the       participants
Whitley           money amount        and skill
(1981)            that should be      components;
                  received, and       procedural
                  matching            fidelity: No.
                  slides.

Wissick,          Photos and          Multiple
Lloyd, &          wrappers of         baseline
Kinzie (1992)     grocery items.      across
                                      participants;
                                      procedural
                                      fidelity: yes.

                  Intervention Description;       Acquisition
                  Length; Error Correction;       Results:
Author            Setting,                        PND

Aeschleman &      Mnemonic training for           85%
Schladenhauffen   making shopping list,
(1984)            verbal instruction, & role
                  play; 13 sessions,
                  modeling; classroom.

Alcantara         Videotape viewing, on-site      99%
(1994)            prompting, and
                  reinforcement; 16 sessions;
                  least to most prompts; 3
                  school sites--library,
                  classroom, school meeting
                  room, and 3 community
                  sites--grocery store, drug
                  store, and convenience
                  store.

Browder, Snell,   Time delay, combined            86%
& Wildonger       gesture, and verbal
(1988)            direction; 11 sessions;
                  modeling; classroom and
                  public recreational site.

Colyer &          System of least prompts and     73%
Collins           instructive feedback; 22
(1996)            sessions; modeling; school
                  classrooms or coach's
                  office.

Denny & Test      Verbal instruction &            84%
(1995)            modeling, opportunities for
                  mixed practice; 27 sessions;
                  modeling; school library.

Frank &           NA; 27 sessions; NA;            100%
Wacker (1986)     classroom; no details
                  provided, just mentions
                  training phase.

Fredrick-         Progressive time delay,         88%
Dugan, Test, &    general case strategy to
Vam (1991)        sample the range of stimuli;
                  5 sessions; NA; school
                  library, department store.

Gardill &         Time delay, multiple            83%
Browder           exemplars of stimuli, &
(1995)            stimulus prompt (money
                  picture); 29 sessions;
                  modeling; classroom, staff
                  lounge, school cafeteria.

Gaule,            Least-to-most prompt            95%
Nietupski, &      procedure; 14 sessions;
Certo (1985)      verbal to physical guidance;
                  classroom and a
                  supermarket.

Haring, Breen,    System of least prompts         97%
Weiner,           during in vivo training;
Kennedy, &        instructor modeling during
Bednersh          videotape answer and
(1995)            question sessions; 33
                  sessions; modeling; 7 stores
                  for each participant

Haring,           Least-to-most prompting         77%
Kennedy,          procedure, videotaped
Adams, &          generalization training; 26
Pitts-Conway,     sessions; verbal to partial
(1987)            physical guidance;
                  classroom and one real
                  setting (school cafe or
                  convenience store); video
                  training occurred in school
                  library or home

Marholin,         Graduated prompting,            81%
O'Toole,          modeling, corrective
Touchette,        feedback, reinforcement,
Berger, &         behavioral rehearsal, and
Doyle (1979)      time-outs; 11 sessions;
                  modeling; day program
                  workshop, bus, and
                  community shopping
                  center.

Matson &          Verbal instruction,             94%
Long (1986)       modeling, feedback, social
                  and tangible reinforcement,
                  participant modeling, and
                  self-evaluation; 26
                  sessions; modeling;
                  classroom and a
                  community grocery store.

McDonnell         Constant time delay or          Time delay:
(1987)            increasing prompt hierarchy     97%;
                  training; 17 sessions;          Increasing
                  modeling; community fast -      prompt
                  food restaurant and             hierarchy:
                  convenience store.              94%

McDonnell &       Next-dollar pretraining,        GC in vivo:
Ferguson          general case (GC) in vivo       100%
(1988)            or GC simulation plus in        GC simulated
                  vivo training; 6 sessions;      plus in vivo:
                  modeling; classroom and 3       94%.
                  community fast-food
                  restaurants.

McDonnell,        Classroom role playing          Flash card:
Homer, &          (RP) with flashcards of the     0%;
Williams,         purchase amount,                Slides: 40%;
(1984)            classroom RP with slides of     Slides plus in
                  cash registers showing          vivo: 100%.
                  different amounts, and RP
                  with slides & in vivo
                  training; 9 sessions;
                  modeling & physical
                  guidance; classroom and a
                  grocery store.

McDonnell &       Backward chain or               Backward
Laughlin          concurrent chain training,      chain or
(1989)            decreasing prompt               concurrent
                  hierarchy; 24 sessions;         chain
                  physical guidance;              training: 99%.
                  community supermarket
                  and fast-food restaurant.

Morse &           In vivo training using          82% (data
Schuster          constant time delay and         available for 8
(2000)            simulation training with        participants
                  pictorial story board; 12       who
                  sessions; modeling;             completed
                  classroom and grocery           study before
                  store.                          the end of the
                                                  semester).

Nietupski,        Modeling, picture               72%
Clancy, &         prosthetic card; 13
Christiansen      sessions; modeling
(1984)            followed by student
                  imitating; elementary,
                  junior high school, and
                  community shopping mall.

Nietupski,        Modeling the use of the         100%
Welch, &          picture prompt money card
Wacker,           and the subtraction
(1983)            calculator procedure; 31
                  sessions; verbal to physical
                  guidance; school office.

Schlein,          Verbal prompt and               86%
Certo, &          feedback; 20 sessions;
Muccino,          modeling to physical
(1984)            guidance; community
                  bowling alley.

Schloss,          Least to most prompts, peer     92%
Kobza, &          tutoring, general case
Alper (1997)      instruction; 12 sessions;
                  modeling; classroom.

Smeets (1978)     Modeling & reinforcement;       75%
                  40 sessions; modeling; a
                  simulated special room.

Sprague, &        Most to least prompt            87%
Horner (1984)     system, single case vs.
                  multiple case vs. general
                  case instruction; 6 sessions;
                  modeling to physical
                  guidance; classroom, high
                  school hallway, community
                  recreation facility, hospital
                  lobby, laundromat, and a
                  public lunch room.

Storey, Bates,    System of least-to-most         99%
& Hanson          prompts with social
(1984)            reinforcement; 11 sessions;
                  modeling; community
                  restaurants.

Test, Howell,     Verbal instruction and          85%
Burkhart, &       modeling; 12 sessions;
Beroth (1993)     verbal & model prompts;
                  participants' homes and
                  school library.

Van den Pol,      Simulated training using        86%
Iwata,            modeling and role-playing
Ivancic, Page,    with social reinforcement;
Neef, &           19 sessions; instructive
Whitley           feedback and remedial
(1981)            trials; classroom.

Wissick,          Interactive videodisc           90%
Lloyd, &          simulation, modeling, and
Kinzie (1992)     verbal prompts, least
                  prompts strategy; 16
                  sessions; verbal to physical
                  guidance; high school
                  classroom.

                  Maintenance            Generalization
                  Results:               Results:
Author            PND                    PND

Aeschleman &      Post-training          Majority of the
Schladenhauffen   scores were            skill components
(1984)            maintained for 3 of    showed
                  the 4 participants     generalization to
                  for at least 5         two new
                  months: 100%.          environments:
                                         100%.

Alcantara         All participants       After training in 2
(1994)            maintained skills 2    stores, all students
                  weeks post-            increased their
                  training: 100%.        level of
                                         performance in the
                                         3rd store during
                                         the baseline.
                                         Generalization
                                         was not assessed.

Browder, Snell,   Maintenance            Generalized skills
& Wildonger       probes taken 2-3       to untrained sites:
(1988)            weeks later were       78%.
                  available for 2 of 4
                  participants:
                  100%.

Colyer &          2 of the 4             2 out of the 4
Collins           participants           participants
(1996)            maintained skill       generalized skills
                  for up to 4 probe      to the community:
                  sessions: 75%.         50%.

Denny & Test      All three students     2 out of 3 students
(1995)            maintained taught      improved their
                  skill for 10 weeks:    purchasing skills
                  100%.                  in one community
                                         site: Data not
                                         graphed.

Frank &           Maintained skills      Generalized skills
Wacker (1986)     over a 4-week          to the school
                  interval: 91%.         store: 94%.

Fredrick-         Both participants      Purchasing
Dugan, Test, &    maintained newly       behaviors
Vam (1991)        acquired skills        generalized to 2
                  over a 4-week          untrained
                  period: 100%.          community sites:
                                         100%.

Gardill &         NA                     2 of the 3
Browder                                  participants
(1995)                                   generalized to
                                         community stores;
                                         the third showed
                                         partial
                                         generalization:
                                         Linear graph data
                                         not provided.

Gaule,            Newly acquired         NA
Nietupski, &      skills were
Certo (1985)      partially
                  maintained over a
                  4-week period:
                  100%.

Haring, Breen,    A majority of          Generalized to
Weiner,           participants           novel stores:
Kennedy, &        maintained skills 3    86%
Bednersh          weeks later: 100%.
(1995)

Haring,           Participants           Generalized to 3
Kennedy,          independently          community
Adams, &          purchased items        stores before
Pitts-Conway,     for a majority of      video training of
(1987)            the probes at 1        these stores:
                  week and 2 weeks       17%; After video
                  after training:        training: 100%.
                  100%.

Marholin,         NA                     Generalized
O'Toole,                                 restaurant
Touchette,                               purchasing skills
Berger, &                                to untrained
Doyle (1979)                             restaurant: 88%.

Matson &          Gains by all           Skills generalized
Long (1986)       participants           to an untrained
                  maintained at a        store: 100%.
                  2-month follow-up:
                  100%.

McDonnell         NA                     NA
(1987)

McDonnell &       NA                     Both strategies
Ferguson                                 showed
(1988)                                   generalized
                                         performance in
                                         3 fast-food
                                         restaurants:
                                         100%.

McDonnell,        NA                     Generalized
Homer, &                                 performance in
Williams,                                5 untrained
(1984)                                   grocery stores:
                                         Flash card: 0%;
                                         Slides: 40%;
                                         Slides plus in
                                         vivo: 100%.

McDonnell &       Maintenance data       NA
Laughlin          available for 3 of
(1989)            the 4 participants
                  showed maintenance
                  of skill:
                  100%.

Morse &           6 participants who     6 participants
Schuster          reached criterion      improved their
(2000)            maintained skills      performance in a
                  for up to 6 weeks:     similar store
                  100%.                  with one session
                                         of on-site
                                         training: Data
                                         not graphed.

Nietupski,        Skill maintenance      Partially
Clancy, &         occurred for 3 of      generalized to
Christiansen      the 4 participants     untrained
(1984)            up to 6 weeks:         vending
                  100%.                  machines: Data
                                         not graphed.

Nietupski,        Maintenance data       Training in
Welch, &          were available for     school
Wacker,           3 of 4                 generalized to
(1983)            participants:          supermarket for
                  100%.                  all participants:
                                         100%.

Schlein,          NA                     Generalized to
Certo, &                                 similar
Muccino,                                 environment:
(1984)                                   100%.

Schloss,          NA                     5 out of 6
Kobza, &                                 students made
Alper (1997)                             purchases in
                                         community
                                         settings: 83%.

Smeets (1978)     NA                     NA

Sprague, &        18 months after        Single case:
Horner (1984)     study, 5 of the 6      67%
                  students were still    Multiple case:
                  carrying a             50%
                  prosthetic card        General case:
                  and regularly          95%.
                  using quarters to
                  purchase items
                  from vending
                  machines:
                  Data not graphed.

Storey, Bates,    All participants       Generalization
& Hanson          maintained skills      was assessed
(1984)            at both a 2-month      across two
                  and a 5-month          similar sites and
                  follow-up              one dissimilar
                  assessment:            site: 83%.
                  100%.

Test, Howell,     All 3 students in      All 3 students in
Burkhart, &       Expt. 2                Expt. 2
Beroth (1993)     maintained skills      successfully
                  11 weeks later:        purchased a
                  100%.                  snack in a food
                                         court: Data not
                                         graphed.

Van den Pol,      Newly acquired         All participants
Iwata,            skills were            generalized skill
Ivancic, Page,    maintained 1 year      to community
Neef, &           later: 100%.           restaurant (e.g.,
Whitley                                  McDonalds,
(1981)                                   Burger King):
                                         100%.

Wissick,          Participants           Participants
Lloyd, &          maintained skills      made purchases
Kinzie (1992)     for 5 weeks: 67%.      at a local
                                         grocery store
                                         and 4
                                         convenience
                                         stores: 60%.

Note. CA = chronological age in years; CBI = community-based
instruction; Expt. = experiment; IQ = intelligence quotient;
MR = mental retardation; NA = not available.

TABLE 2
Summary of Purchasing/Functional Mathematics Intervention Effects
by Study Features

                                               Median
Study Feature                             n     PND     Range

Participant Characteristics

Grade
  Elementary & middle                      8     92     72-100
  Secondary                               14     87     59-100
  Postsecondary                            6     90      75-99
Disability Category
  Mild and moderate                        8     86     72-100
  Moderate and severe                     17     88     59-100
  Other (e.g., Autism)                     3     83      77-97
Entry Skills *
  Money recognition                        9     94     73-100
  Community experience                    10     85      59-99
  None reported                            9     87     77-100

Purchasing Instructional Features

Purchasing Skill Instructional Strategy
  Modeling/verbal instruction              9     85     72-100
  Faded prompt procedure                  18     89      59-99
  Not reported                             1    100       NA
Money Skill Adaptation *
  Simplification                          13     95     72-100
  Next-dollar strategy                     9     85      59-97
  Calculator use                           4     91     75-100
  Other                                    2     82      81-83
Type of Purchase *
  Restaurant                               6     91      81-99
  Grocery/dept store                      13     94     59-100
  Vending machine/$ skill only             8     83      72-92
Error Correction **
  Verbal instruction/modeling             10     84      72-99
  Physical guidance                       15     92     59-100
  Not reported                             3     94     88-100
Length of Treatment
  Short                                   13     86      59-99
  Long                                    15     90     73-100

Instructional Setting *
  Simulated                               11     85      0-100
  In vivo                                  9     87     72-100
  Simulated + In vivo                     11     94     75-100

Generalization (a)
  Programmed for generalization           10     95     40-100
  Not programmed for generalization       11     83      0-100

Maintenance (b)
  Probes taken within 1 month              9    100     75-100
  Probes taken beyond 1 month             10    100     67-100

Note. n = number of PND scores; PND = percentage of nonoverlapping
data points; (a) = only 21 interventions reported generalization
data; (b) = only 19 interventions reported maintenance data.
* p < .05; ** p < .01.
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