If a potential treatment effect is seen in one tier, the researcher cannot refer to data from the same day in an untreated tier because the tiers are not synchronized in real time and may not even overlap in real time. As a result, concurrent and nonconcurrent designs are virtually identical in their control for maturation threats. If the baseline phase provides sufficiently stable data to support a strong prediction of the subsequent data path and the data path prediction is contradicted by the actual data after the introduction of the independent variable, this provides some suggestion that the independent variable may have been the cause of the changea potential treatment effect. For example, two rooms in the same treatment center would share more coincidental events than a room in a treatment center and another room at home. Recognizing these three dimensions of lag has implications for reporting multiple baseline designs. Perhaps a more general and powerful triad of processes that support demonstration of experimental control would be prediction, contradiction, and replication. Strategies and tactics of behavioral research and practice (4th ed.). Given this dilemma, priority should be given to optimizing the within-tier comparisons because this is the comparison that can confer stronger control. Perspectives on Behavior Science, 43, 605616. Both concurrent and nonconcurrent multiple baseline designs also afford the same across-tier comparison; both can show a potentialtreatment effect after a certain number of baseline sessions in one tier and a lack of effect after that same number of sessions in another tier. Basic Books. Rather, the passage of time allows for more opportunities for participants to interact with their environmentleading to maturational changes. Perspect Behav Sci 45, 647650 (2022). 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. Campbell, D. T., & Stanley, J. C. (1963). According to conventional wisdom, concurrent multiple baselines are superior because they allow for across-tier comparisons that can rule out coincidental events. However, researchers in clinical, educational, and other applied settings recognized that they could expand research much further if the tiers of a multiple baseline could be conducted as they became available sequentially rather than simultaneously. Thus, the additional temporal separation that is possible in a nonconcurrent design is a strength rather than a weakness in controlling for coincidental events. National Center for Biotechnology Information Single-case research designs: Methods for clinical and applied settings (3rd ed.). 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. Instead, a detailed understanding of how specific threats to internal validity are addressed in multiple baseline designs and specific design features that strengthen or weaken control for these threats are needed. The Nonconcurrent Multiple-Baseline Design: It is What it 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 et al. For example, instrumentation is addressed primarily through observer training, calibration, and IOA. These baseline-treatment comparisons, which we will refer to as tiers, differ from one another with respect to participants, behaviors, settings, stimulus materials, and/or other variables. Psychological Methods, 17(4), 510550. Houghton Mifflin. The authors argue that like the concurrent multiple baseline design, the nonconcurrent form can rule out coincidental events (i.e., history) as a threat to internal validity and that experimental control can be established by the replication of the within-tier comparison with phase changes offset relative to the beginning of baseline. Single-case intervention research design standards. Thus, to demonstrate experimental control, the effects of the independent variable must not generalize; and to detect an extraneous variable through the across-tier comparison, the effects of that extraneous variable must generalize. We can strongly argue that all tiers contact testing and session experience during baseline because we schedule and conduct these sessions. Cooper et al. Type I Errors and Power in Multiple Baseline Designs, Assessing consistency of effects when applying multilevel models to single-case data. Additional replications further reduce the plausibility of extraneous variables causing change at approximately the same time that the independent variable is applied to each tier. Behavior Research Methods, 43(4), 971980. Multiple baseline procedure. The across-tier comparison of concurrent multiple baseline designs is less certain and definitive than it may appear. However, we can never ensure that any two contexts or any two session times are not subject to unique events during the study. write that after implementing the treatment in an initial tier, the experimenter perhaps notes little or no change in the other baselines (p. 94). This comparison may reveal a likely maturation effect. If a potential treatment effect is observed in the treated tier but a change in the dependent variable is also observed in corresponding sessions in a tier that is still in baseline, this provides evidence that an extraneous variable may have caused both changes. In this design, behavior is measured across either multiple individuals, behaviors, or settings. Article 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. Each of these three types of threats point us to distinct dimensions of the lag between phase changes that must be controlled for in order to achieve experimental control: for maturation, we control for elapsed time (e.g., days); for testing and session experience, we must be concerned with the number of sessions; and for coincidental events, we must be concerned with the specific time periods (i.e., calendar dates) of the study. Strategies and tactics of behavioral research. Any alternative explanation of this pattern of results would have to posit an alternative set of causes that could plausibly result in changes in the dependent variable in this specific pattern across the multiple tiers. For example, in a study of language skills in typically developing 3-year-old children, maturation would be a particular concern. Routledge/Taylor & Francis Group. Behavioral Interventions, 33(2), 160172. Kazdin, A. E. (2021). They then describe the multiple baseline technique (p. 94) and two types of comparisons that contribute to its experimental control. Kazdin, A. E., & Kopel, S. A. In this highly influential early textbook on SCD, Hersen and Barlow describe only the across-tier analysis and fail to mention replicated within-tier comparisons. This assumption was initially identified by Kazdin and Kopel in 1975, but its implications for the rigor of the across-tier comparison have rarely been discussed since that time. Nonconcurrent multiple baseline designs, however, do not afford this comparison. Reasons for these specifications will become clear later in the article.) On resolving ambiguities of the multiple-baseline design: Problems and recommendations. Thus, although the across-tier analysis does provide a test of the maturation threat, a lack of change in untreated tiers cannot definitively rule it out. Design WebMULTIPLE BASELINE DESIGN Most widely used for evaluating treatment effects in ABA Highly flexible Do not have to withdraw treatment variable Is an alternative to reversal https://doi.org/10.1177/001440290507100203, Johnston, J. M., Pennypacker, H. S., & Green, G. (2020). Research methodologists have identified numerous potential alternative explanations that are threats to internal validity (e.g., Campbell & Stanley, 1963; Cooper et al., 2020; Kazdin, 2021; Shadish et al., 2002). Thus, for any multiple baseline design to address the threat of maturation, it must show changes in multiple tiers after substantially differing numbers of days in baseline. 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. Applied behavior analysis (3rd ed.). Under these conditions, the experimental rigor of concurrent multiple baselines is identical to nonconcurrent multiple baselines; coincidental events that contact a single tier cannot be detected by an across-tier analysis. Natural multiple baselines across persons: A reply to Harris and Jenson. However, this kind of support is not necessary: lagged replications of baseline predictions being contradicted by data in the treatment phase provide strong control for all of these threats to internal validity. A : true B : false. Multiple Baseline Designs Journal of Behavioral Education, 13(4), 267276. Routledge/Taylor & Francis Group. However, it does not rule out maturation as an alternative explanation of the change in behavior. https://doi.org/10.1002/bin.1510. The author has no known conflicts of interest to disclose. Timothy A. Slocum. (2018) state: Confidence that maturation and history [coincidental events] threats are under control is based on observing (a) an immediate change in the dependent variable upon introduction of the independent variable, and (b) baseline (or probe) condition levels remaining stable while other tiers are exposed to the intervention. That is, session numbers do not necessarily correspond to the same periods of real time across tiers. Carr, J. E. (2005). Data analysis issues concern two closely related questions: (1) Was there a change in data patterns after the phase change? For example, knowing the date of session 10 in tier 1 tells us nothing about the date of session 10 in tier 2. This control assumes that the replications are sufficiently offset in real time (e.g., calendar days) to ensure that a single coincidental event could not plausibly cause the effects observed in multiple tiers. They state, the nonconcurrent multiple baseline across participants design is inherently weaker than other multiple baseline design variations. 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. Hersen, M., & Barlow, D. H. (1976). https://doi.org/10.1177/0741932512452794, Lanovaz, M. J., & Turgeon, S. (2020). Poor execution can certainly worsen these problems, but good execution cannot eliminate them. We have no known conflict of interest to disclose. Oxford University Press. This insensitivity is not due to poor experimental design or implementation, it is built in to the nature of multiple baseline designs across participants. Tactics of scientific research. For example, it is implausible that the effects of maturation would coincide with a phase change after 5 days in one tier, after 10 days in a second tier, and after 15 days in a third. They do not mention the across-tier comparison, presumably because they believe that this analysis is not necessary to establish experimental control. Maturation refers to extraneous variables such physical growth, physiological changes, typical interactions with social and physical environments, academic instruction, and behavior management procedures that tend to cause changes in behavior over time (cf., Shadish et al., 2002). and (2) Was any change the result of the independent variable? WebLike RCTs, the multiple baseline design can demonstrate that a change in behavior has occurred, the change is a result of the intervention, and the change is significant. Multiple baseline and changing criterion design Flashcards The nature of control for coincidental events (i.e., history) provided by the within-tier comparison in both concurrent and nonconcurrent multiple baseline designs is relatively straightforward. Behavioral Assessment, 7(2), 129132. Experimental and quasi-experimental designs of research. https://doi.org/10.1007/s40614-022-00343-0, DOI: https://doi.org/10.1007/s40614-022-00343-0. This provides clear information about the number of sessions that precede the phase change in each tier, and therefore constitutes a strong basis for controlling the threat of testing and session experience. 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. Any one tier may, at best, demonstrate a potential treatment effect; however, a set of three or more tiers may strongly address the threat of coincidental events and clearly demonstrate experimental control. One is that if a Two articles published in 1981 described and advocated the use of nonconcurrent multiple baseline designs (Hayes, 1981; Watson & Workman, 1981). All three of these dimensions of lag are necessary to rigorously control for commonly recognized threats to internal validity and establish experimental control. This understanding of the primary role of replicated within-tier comparisons also implies that, when there is a trade-off, design options that improve control through the within-tier comparisons should take precedence over those that would improve control through across-tier comparisons. 7. 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). B. 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. 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. PubMed Harvey, M. T., May, M. E., & Kennedy, C. H. (2004). https://doi.org/10.1002/bin.191, Article 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. Further, for the across-tier comparison to detect the influence of a coincidental event, that event must not only contact multiple tiers, it must cause similar changes in the dependent measure across multiple tiers. However, ina concurrent multiple baseline across settings a setting-level event would contact only a single tierthe design would be inherently insensitive to these coincidental events. That is, it is not strong evidence verifying the prediction of no change in the initial tier in the absence of an intervention. . 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). Although the design entails two of the three elements of baseline logicprediction and replicationthe absence of concurrent baseline measures precludes the verification of [the prediction]. Google Scholar, Coon, J. C., & Rapp, J. T. (2018). An example of multiple baseline across behaviors might be to use feedback to develop a comprehensive exercise program that involves stretching, aerobic exercise, We are not pointing to flaws in execution of the design; we are pointing to inherent weaknesses. The concurrent multiple baseline design opened up many new opportunities to conduct applied research in contexts that were not amenable to other SCDs. Single-case experimental designs: A systematic review of published research and current standards. When determining whether a multiple baseline study demonstrates experimental control, researchers examine the data within and across tiers and also consider the extent to which alternative explanations (e.g., extraneous variables or confounds) could plausibly account for the obtained data patterns. Textbook authors, editors, and readers of research should consider nonconcurrent multiple baseline designs to be capable of supporting conclusions every bit as strong as those from concurrent designs. 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. Perspect Behav Sci 45, 619638 (2022). For example, for a child who is on the cusp of walking, a month of exposure to maturational variables may result in a significant improvement in walking, but much less change in fine motor skills. 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. Taplin, P. S., & Reid, J. Anyone you share the following link with will be able to read this content: Sorry, a shareable link is not currently available for this article. Creating Single-Subject Research Design Graphs Timothy A. Slocum, P. Raymond Joslyn, Sarah E. Pinkelman, Thomas R. Kratochwill, Joel R. Levin, Esther R. Lindstrm, Marc J. Lanovaz, Stphanie Turgeon, Tara L. Wheatley, Jonathan Rush, Philippe Rast & Scott M. Hofer, Perspectives on Behavior Science It is clear that we cannot claim that these assumptions are always valid for multiple baseline designs. 288335). With stable data, the range within which future data points will fall is Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. 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. For both types of comparisons, addressing maturation begins with an AB contrast in a single tier. Child Development, 44, 547554. volume45,pages 647650 (2022)Cite this article. (p. 365), Of course, the major problem with this [nonconcurrent multiple baseline] strategy is that the control for history (i.e., the ability to assess subjects concurrently) is greatly diminished. 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. Further, for both types of multiple baselines, the threat of coincidental events should be evaluated primarily based on replicated within-tier comparisons. Pergamon. limitation of alternating treatment designs: o it is susceptible to multiple treatment interference, o rapid back-and-forth switching of treatments does not reflect the typical manner in which interventions are applied and may be viewed as artificial and undesirable. . . Journal of Behavioral Education, 13(4), 213226. If these assumptions are not valid, then it would be possible to observe stable baselines in untreated tiers even though the change in the treated tier was a result of an extraneous variable. 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. Department of Educational Psychology, Neag School of Education, University of Connecticut, Storrs, CT, 06269, USA, You can also search for this author in multiple Cooper, J. O., Heron, T. E., & Heward, W. L. (2020). This has been the topic of important recent methodological research, including studies of the interobserver reliability of expert judgements of changes seen in published multiple baseline designs (Wolfe et al., 2016) and use of simulated data to test Type I and II error rates when judgements of experimental control are made based on different numbers of tiers (Lanovaz & Turgeon, 2020).
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