multiple baseline design disadvantages

(p. 325), Compared to its concurrent multiple baseline design sibling, a non-concurrent arrangement is inherently weaker . Coincidental events (i.e., history) are specific events that occur at a particular time (or across a particular period) and could cause changes in behavior. Behavioral Interventions, 33(2), 160172. The general steps for the development of the line graphs are as follows: 1. For example, in a study of language skills in typically developing 3-year-old children, maturation would be a particular concern. WebWeaknesses of multiple baseline designs: There are certain functional relations that may not be clearly understood by this design This design is time consuming and The across-tier comparison is valuable primarily when it suggests the presence of a threat by showing a change in an untreated tier at approximately the same time (i.e., days, sessions, or dates) as a potential treatment effect. Pearson. Coincidental events include divorce, changing of living situation, changes in school or work schedule, physical injury, changes in a setting such as construction, changes in coworkers or staffing, and many others. PubMed All three of these dimensions of lag are necessary to rigorously control for commonly recognized threats to internal validity and establish experimental control. With control for coincidental events in multiple baseline designs resting squarely on replicated within-tier comparisons, there is no basis for claiming that, in general, concurrent designs are methodologically stronger than nonconcurrent designs. (2022), Revisiting an Analysis of Threats to Internal Validity in Multiple Baseline Designs, Moderation analysis in two-instance repeated measures designs: Probing methods and multiple moderator models, Examining and Enhancing the Methodological Quality of Nonconcurrent Multiple-Baseline Designs, How Many Tiers Do We Need? For example, Gast et al. In both forms of multiple baseline designs, a potential treatment effect in the first tier would be vulnerable to the threat that the changes in data could be a result of testing or session experience. The multiple baseline design is useful for interventions that are irreversible due to learning effects, and when treatment cant be withdrawn. Google Scholar, Coon, J. C., & Rapp, J. T. (2018). First, in the replicated within-tier comparison, each tier of the design is exposed to the treatment at a different point in time. Hersen and Barlows (1976) textbook appears to be the first complete description of the multiple baseline design with many of the ideas about experimental control that are current to this day. On the other hand, across-tier comparisons may be strengthened by arranging tiers to be as similar as possible so that they would be more likely to be exposed to the same coincidental events. https://doi.org/10.1002/bin.191, Article Application of multiple baseline designs in behavior analytic research: Evidence for the influence of new guidelines. In concurrent multiple baseline across participants, behaviors, or stimulus materials that take place in a single setting, this kind of event would contact all the tiers of the multiple baseline. We can identify at least three general categories of issues that influence the number of tiers required to render threats implausible: challenges associated with the phenomena under study, experimental design features, and data analysis issues. Kennedy, C. H. (2005). The details of situations in which this across-tier comparison is valid for ruling out threats to internal validity are more complex than they may appear. Rand McNally. Each tier involves a unique participant and there is a class of coincidental events that contact a single participant. WebThe first quality of ideal baseline data is stability, meaning that they display limited variability. If this patterna clear prediction from baseline being contradicted when and only when the independent variable is introducedcan be replicated across additional tiers of the multiple baseline, then the evidence of a treatment effect is incrementally strengthened. The vast majority of contemporary published multiple baseline designs describe the timing of phases in terms of sessions rather than days or dates. Houghton Mifflin. Every multiple baseline design in which potential treatment effects are observed in some but not all tiers demonstrates that tiers are not always equally sensitive to interventions. The dimension of time is recognized in the requirement that phase changes be lagged in real timethat is, the date on which the phase changes are made. Wacker, D., Berg, W., Harding, J., & Cooper-Brown, L. (2004). https://doi.org/10.1177/0145445516644699, Department of Special Education & Rehabilitation Counseling, Utah State University, 2865 Old Main Hill, Logan, UT, 84322, USA, Timothy A. Slocum,Sarah E. Pinkelman,P. Raymond Joslyn&Beverly Nichols, You can also search for this author in We are not pointing to flaws in execution of the design; we are pointing to inherent weaknesses. The across-tier comparison of concurrent multiple baseline designs is less certain and definitive than it may appear. Nonconcurrent multiple baseline designs and the evaluation of educational systems. Learn more about Institutional subscriptions. Child Development, 44, 547554. . They do not mention the across-tier comparison, presumably because they believe that this analysis is not necessary to establish experimental control. They then describe the multiple baseline technique (p. 94) and two types of comparisons that contribute to its experimental control. A : true B : false. This consensus is that nonconcurrent multiple baseline designs are substantially weaker than concurrent designs (e.g., Cooper et al., 2020; Johnston et al., 2020; Kazdin, 2021). In addition, arranging tiers that are isolated in other dimensions (e.g., location, behaviors, participants) confers overall strength, not weakness, for addressing coincidental events. In general, in a concurrent multiple baseline design across any factor, the across-tier analysis is inherently insensitive to coincidental events that are limited to a single tier of that factor. Barlow, D. H., Nock, M. K., & Hersen, M. (2009). A close examination of threats to internal validity in multiple baseline designs reveals and clarifies the critical design features that determine the degree of experimental control and internal validity of either type of multiple baseline. Routledge/Taylor & Francis Group. (1975). Any of these types of circumstances may require additional tiers in order to clearly address threats to internal validity. Single-case experimental designs: Strategies for studying behavior change. Finally, we make recommendations for more rigorous use, reporting, and evaluation of multiple baseline designs. Watson and Workman (1981) noted that the requirement that observations be taken concurrently clearly poses problems for researchers in applied settings (e.g., schools, mental health centers), since clients with the same target behavior may only infrequently be referred at the same point in time (p. 257). https://doi.org/10.3758/s13428-011-0111-y, Article Exceptional Children, 71, 165179. The assumption that maturation contacted all tiers is strongparticipants were all exposed to maturational variables (i.e., unidentified biological events and environmental interactions) for the same amount of time. Table 1 summarizes these threats to internal validity and the dimension of lag necessary to control for each. The author has no known conflicts of interest to disclose. Department of Educational Psychology, Neag School of Education, University of Connecticut, Storrs, CT, 06269, USA, You can also search for this author in Without these dimensions of lag explicitly stated in the definition, we cannot claim that multiple baseline designs will necessarily include the features required to establish experimental control. volume45,pages 647650 (2022)Cite this article. Part of Springer Nature. We use function of elapsed time descriptively rather than causally. Peer reviewers and editors who serve as gatekeepers for the scientific literature must also have a deep understanding of these issues so that they can distinguish between stronger and weaker research, ensure that information critical to evaluating internal validity is included in research reports, and assess the appropriateness of discussion and interpretation of results. Neither the within-tier comparison, nor the across-tier comparison depends on the tiers being conducted simultaneously; both types of comparisons only require that phase changes occur after substantially different amounts of time since the beginning of baselinethat is, each tier is exposed to different amounts of maturation (i.e., days) prior to the phase change. According to conventional wisdom, concurrent multiple baselines are superior because they allow for across-tier comparisons that can rule out coincidental events. And researchers generally design and implement interventions, select tiers, and employ measures that will likely show consistent treatment effects. However, critics of nonconcurrent designs have rarely (1) made a thorough and critical analysis of the potential weaknesses of across-tier comparisons in concurrent multiple baselines, or (2) evaluated the degree of experimental control that can be demonstrated by replicated within-tier comparisons. Perspect Behav Sci 45, 619638 (2022). We challenge this assertion. In this case, the across-tier comparison would give the false appearance of strong internal validity. Potential setting-level events include staffing changes in classroom, redecoration or renovation of the physical environment, and changes in the composition of the peer group in a classroom, group home, or worksite. In the current study, it is likely that exposure to some of the measures can affect scores on other measures or repeated exposure to a measure can lead to socially desirable responding or A study may be at heightened risk of coincidental events if the target behavior is particularly sensitive to events in the environment that are uncontrolled by the experimenter. https://doi.org/10.4324/9781315150666, Chapter Perspect Behav Sci 45, 647650 (2022). Multiple baseline and multiple probe designs. Behavior Modification, 40(6), 852873. Given that multiple baseline designs make up such a large proportion of the existing SCD literature and current research activity, it is critical that SCD researchers thoroughly understand the specific ways that multiple baseline designs address potential threats to internal validity so that they can make experimental design decisions that optimize internal validity and accurately evaluate, discuss, and interpret the results of their research. Throughout their discussion of SCD, these authors describe experimental control in terms of three processes: prediction, verification, and replication. Consequently, it is often difficult or impossible to dismiss rival hypotheses or explanations. Data from the treatment phase in one tier can be compared to corresponding baseline data in another tier. https://doi.org/10.1016/0005-7916(81)90055-0, Wolfe, K., Seaman, M. A., & Drasgow, E. (2016). This critical requirement is mainly addressed by the lag between phase changes in successive phases. A baseline (A) and an intervention (B) are included in a straightforward AB design psychological experiment (B). et al. These reports do not provide the information necessary to rigorously evaluate maturation or coincidental events. Single-case intervention research design standards. Single-case research designs: Methods for clinical and applied settings (3rd ed.). Three phonological patterns were targeted for each child. Smith (2012) found that SCD was reported in 143 different journals that span a variety of fields such as behavior analysis, psychology, education, speech, and pain management; across these fields, multiple baselines account for 69% of SCDs. Multiple baseline procedure. Slider with three articles shown per slide. The use of continuous assessment and multiple experimental phases in single-subject research designs allow for detailed examinations of They do not elaborate on the importance of this type of comparison. https://doi.org/10.1901/jaba.1968.1-91, Article In both within- and across-tier comparisons, the dates on which the sessions took place are not relevant to the effects of testing and session experience. Applied behavior analysis (3rd ed.). Correspondence to For example, in a multiple baseline across settings, the settings could present somewhat different demands. PubMedGoogle Scholar. After implementing the treatment for the first tier, they say, rather than reversing the just produced change, he instead applies the experimental variable to one of the other as yet unchanged responses. It is possible that a coincidental event may be present for all tiers but have different effects on different tiers. As we argued above, the observation of no change in an untreated tier is not strong evidence against a coincidental event affecting the treated tier. B. In particular, within-tier comparisons may be strengthened by isolating tiers from one another in ways that reduce the chance that any single coincidental event could coincide with a phase change in more than one tier (e.g., temporal separation). These events would contact all tiers of a MB that take place in that single setting, but not tiers in other settings. Shadish, W. R., Cook, T. D., & Campbell, D. T. (2002). The lag between phase changes must be long enough that maturation over any single amount of time cannot explain the results in multiple tiers. By nature, undetected events are unknown. volume45,pages 619638 (2022)Cite this article. Single-case designs for educational research. This question cannot be addressed by data analysis alone; any pattern of data, no matter how dramatic, could be a result of an extraneous variable if the experimental design features are not properly arranged. because a non-concurrent design does not allow any AB comparisons across baselines, it omits the opportunity to see if responding under the control condition changes when the treatment condition is implemented in the other baseline. Ten sessions of baseline would be expected to have similar effects whether they occur in January or June. If a nonconcurrent multiple baseline has a long lag in real time between phase changes (e.g., weeks or months), this may provide stronger control than a design with a lag of one or several days. Type I errors and power in multiple baseline designs. They state, the nonconcurrent multiple baseline across participants design is inherently weaker than other multiple baseline design variations. An alternative explanation would have to suggest, for example, that in one tier, experience with 5 baseline sessions produced an effect coincident with the phase change; in a second tier, 10 baseline sessions had this effect, again coinciding with the phase change; and in a third tier, 15 baseline sessions produced this kind of change and happened to correlate with the phase change. a potential treatment effect in the first tier would be vulnerable to the threat that the changes in data could be a result of They never raise the question of whether replicated within-tier comparisons are sufficient to rule out threats to internal validity and establish experimental control. Oxford University Press. WebDisadvantages to Multiple Baseline Designs -Weaker method of showing experimental control than a reversal (b/c no withdrawal of treatment) -Delay in treatment can occur as For example, physical growth and experiences with the environment can accumulate and result in relatively sudden behavioral changes when a toddler begins to walk. Instead, the idea that lag across phase changes includes three important dimensions and that these lags are critical for establishing experimental control and justifying strong causal conclusions should be elevated in importance. Events that contact a single participant may be termed participant-level. (Our specification of phase change offset in terms of real time, days in baseline, and sessions in baseline is unusual. The authors discuss two designs commonly used to demonstrate reliable control of an important behavior change (p. 94). Recognizing these three dimensions of lag has implications for reporting multiple baseline designs. (1973). This has at least two effects: first, the multiple baseline is seen as weaker than the withdrawal design because of this dependence on the across-tier analysis; and second, when nonconcurrent multiple baseline designs are introduced years later, their rigor will be understood by many methodologists in terms of control by across-tier comparisons only, without consideration of replicated within-tier comparisons. We recommend that multiple baseline design be defined as a single-case experimental design that evaluates causal relations through multiple baseline-treatment comparisons with phase changes that are sufficiently offset in (1) real time (i.e., calendar date), (2) number of days in baseline, and (3) number of sessions in baseline. This has been the sharpest point of criticism of nonconcurrent multiple baselines. Campbell, D. T., & Stanley, J. C. (1963). In J. R. Ledford & D. L. Gast (Eds. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. When he turned to multiple baseline designs, Hayes argued that AB designs are natural to clinic work and that forming a multiple baseline can consist of collecting several AB replications, which would inevitably have differing lengths of baseline (i.e., a nonconcurrent multiple baseline; p. 206). In a review of the SCD literature, Shadish and Sullivan (2011) found multiple baseline designs making up 79% of the SCD literature (54% multiple baseline alone, 25% mixed/combined designs). Single case experimental designs: Strategies for studying behavior change (3rd ed.). (pp. Psychological Methods, 17(4), 510550. We will focus on the three types of threats that are addressed through comparisons between baseline and treatment phases in multiple baseline designs: maturation, testing and session experience, and coincidental events.Footnote 1. Watson and Workman did not explicitly address threats to internal validity other than coincidental events. Use the Previous and Next buttons to navigate the slides or the slide controller buttons at the end to navigate through each slide. He acknowledged that earlier authors had stated that multiple baselines must be concurrent and he noted that in a nonconcurrent multiple baseline the across-tier comparison could not reveal coincidental events. Controlling for coincidental events requires attention to the specific dates on which events occur. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. Journal of Behavioral Education, 13(4), 213226. As Kazdin and Kopel (1975) pointed out, multiple baseline designs require that the effects of the independent variable must have tier-specific effects, yet the across-tier analysis requires that extraneous variables must not have tier-specific effects. As Kazdin and Kopel point out, it is clearly possible for treatments to have broad effects on multiple tiers and for extraneous variables to have narrow effects on a specific tier. On resolving ambiguities of the multiple-baseline design: Problems and recommendations. Provided by the Springer Nature SharedIt content-sharing initiative, Over 10 million scientific documents at your fingertips, Not logged in This skepticism of nonconcurrent designs stems from an emphasis on the importance of across-tier comparisons and relatively low importance placed on replicated within-tier comparisons for addressing threats to internal validity and establishing experimental control. However, it does not rule out maturation as an alternative explanation of the change in behavior. Coincidental events might be expected to be more variable in their effect than interventions that are designed to have consistent effects. To offer some guidance, we believe that under ideal conditionsadequate lags between phase changes, circumstances that do not suggest that threats are particularly likely, and clear results across tiersthree tiers in a multiple baseline can provide strong control against threats to internal validity. Poor execution can certainly worsen these problems, but good execution cannot eliminate them. There is ample empirical evidence of differential impact of variables across tiers. However, the specific issues in this controversy have never been thoroughly identified, discussed, and resolved; and instead a consensus emerged without the issues being explicitly addressed. We examine how these comparisons address maturation, testing and session experience, and coincidental events. Kazdin, A. E. (2021). (1968) who emphasized the replicated within-tier comparison. The multiple baseline family of designs includes multiple baseline and multiple probe designs. Although many maturational changes are gradual, more sudden changes are possible. We use the term potential treatment effect to emphasize that the evidence provided by this single AB within-tier comparison is not sufficient to draw a strong causal conclusion because many threats to internal validity may be plausible alternative explanations for the data patterns. This information would allow readers to evaluate the sufficiency of each dimension of lag given the specific characteristics of the particular study. The definition states that there must be sufficient lag between phase changesthis is not further specified because the amount of lag necessary to ensure that any single amount of maturation, number of sessions, or coincidental event could not cause changes in multiple tiers must be determined in the context of the particular study. However, as Hayes (1985) pointed out, even with the most rigorous care in experimental design, we can never give two individuals the same experiences outside of our experimental sessions. Behavior Therapy, 6(5), 601608. Maturational changes may be smooth and gradual, or they may be sudden and uneven. In this article, we argue that the primary reliance on across-tier comparisons and the resulting deprecation of nonconcurrent designs are not well-justified. Predi Abab Design Essay Two articles published in 1981 described and advocated the use of nonconcurrent multiple baseline designs (Hayes, 1981; Watson & Workman, 1981). Correspondence to Hayes argued that fortunately the logic of the strategy does not really require (p. 206) an across-tier comparison because the within-tier comparison rules out these threats. Provided by the Springer Nature SharedIt content-sharing initiative, Over 10 million scientific documents at your fingertips, Not logged in WebNew Mexico's Flagship University | The University of New Mexico An important question for researchers, reviewers, and readers of research is whether the amount of lag is sufficient for a specific study. Elapsed time does not directly cause maturational changes in behavior. Therefore, researchers must exercise extreme caution in interpreting and generalizing the results from pre-experimental studies. The across-tier comparison provides another possible source of control for maturation. Book This is a significant problem for the across-tier comparison because its logic is dependent on these two assumptions. The withdrawal phase of an A-B-A design is important because it shows that the results of the intervention weren't just a result of a difference in time. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. To understand the ability of concurrent designs to meet these assumptions we must distinguish different types of coincidental events based on the scope of their effects. Threats to Internal Validity in Multiple-Baseline Design Variations. WebWhat are some disadvantages of alternating treatment design? Natural multiple baselines across persons: A reply to Harris and Jenson. By synchronized we mean that session 1 in all tiers takes place before session 2 in any tier, and this ordinal invariance of session number across tiers is true for all sessions. Tactics of scientific research. If each tier of a multiple baseline represents a different participant in a different environment (e.g., school versus clinic) located in a different city, this would further reduce the chance that any single event or pattern of events could have contacted the participants coincident with the phase changes. Having identified the criticisms of nonconcurrent multiple baseline designs, we now turn to a detailed analysis of threats to internal validity and features that can control these threats. Behavior Research Methods, 43(4), 971980. So, similar to maturation, the across-tier comparison is sometimes able to reveal effects of testing and session experience, but it may fail to do so in some circumstances. Longer lags and more isolated tiers can reduce the number of tiers necessary to render extraneous variables implausible explanations of results. However, each replication of the possible treatment effect that takes place at a substantially distinct calendar date reduces the plausibility of this threat. This might be conveniently reported in the methods section or a small table in an appendix. Throughout this article we have argued that controlling for the three main threats to internal validitymaturation, testing and session experience, and coincidental eventsin multiple baseline designs requires attention to three distinct dimensions of lag of phase changes across tiers. Based on the logic laid out in this article, we believe that the treats of maturation and testing and session experience are controlled equivalently in concurrent and nonconcurrent design. Behavioral Interventions, 20(3), 219224. If the pattern of change shortly after implementation of the treatment is replicated in the other tiers after differing lengths of time in baseline (i.e., different amounts of maturation), maturation becomes increasingly implausible as an alternative explanation. the effects of the treatment variable are inferred from the untreated behaviors (p. 227). Additionally, the These could include presence of observers, testing procedures, exposure to testing stimuli, attention from implementers, being removed from the typical setting, exposure to a special setting, and so on. Google Scholar, Harvey, M. T., May, M. E., & Kennedy, C. H. (2004). Other threats to internal validity such as (1) ambiguous temporal precedence, (2) selection, (3) regression, (4) attrition, and (5) instrumentation are addressed primarily through other design features. Thus, to the degree that nonconcurrent designs support longer lags between phases changes than concurrent designs, they may support stronger control of the threat of coincidental events through replicated within-tier comparisons. PubMed Pergamon. The purposes of this article are to (1) thoroughly examine the impact that threats to internal validity can have on concurrent and nonconcurrent multiple baseline designs; (2) describe the critical features of each design type that control for threats to internal validity; and (3) offer recommendations for use and reporting of concurrent and nonconcurrent multiple baseline designs. An example of multiple baseline across behaviors might be to use feedback to develop a comprehensive exercise program that involves stretching, aerobic exercise,

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