While the fact that the researcher does not use a large number of participants has its advantages, it also has a downside: Because the experimental trials are run on only one subject, it is difficult to empirically show with the experiment's data that the findings will generalize out to larger populations. These reports do not provide the information necessary to rigorously evaluate maturation or coincidental events. Kennedy, C. H. (2005). This might be conveniently reported in the methods section or a small table in an appendix. 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]. WebThe first quality of ideal baseline data is stability, meaning that they display limited variability. https://doi.org/10.1007/s40614-022-00343-0, SI: Commentary on Slocum et al, Threats to Internal Validity. 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. 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 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. 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. Strategies and tactics of behavioral research and practice (4th ed.). 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. 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. 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. What are the benefits and problems of these designs? 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. PubMed According to conventional wisdom, concurrent multiple baselines are superior because they allow for across-tier comparisons that can rule out coincidental events. WebNew Mexico's Flagship University | The University of New Mexico This information would allow readers to evaluate the sufficiency of each dimension of lag given the specific characteristics of the particular study. 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. Routledge. That is, session numbers do not necessarily correspond to the same periods of real time across tiers. Part of Springer Nature. This insensitivity is not due to poor experimental design or implementation, it is built in to the nature of multiple baseline designs across participants. 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. 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. For example, Gast et al. 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 When conditions are less ideal, additional tiers may be necessary. Child Development, 44, 547554. The first is the reversal design and the authors describe the important applied limitation with this designsituations in which reversals are not possible or feasible in applied settings. https://doi.org/10.1177/001440290507100203, Johnston, J. M., Pennypacker, H. S., & Green, G. (2020). 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. That is, experimental control has not been convincingly demonstrated. 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). WebDisadvantage: Covariance among subjects may emerge if individuals learn vicariously through the experiences of other subjects Also, identifying multiple subjects in the same The process begins with a simple baseline-treatment (AB) comparisona change from baseline to treatment within a single tier. Characteristics of single-case designs used to assess intervention effects in 2008. 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. Third, we explore how concurrent and nonconcurrent multiple baselines address each of the main threats to internal validity. However, each replication of the possible treatment effect that takes place at a substantially distinct calendar date reduces the plausibility of this threat. In a concurrent multiple baseline that involves a single participant across settings, behaviors, antecedent stimuli etc., this kind of event would be expected to contact all tiers. Estimating reliabilities and correcting for sampling error in indices of within-person dynamics derived from intensive longitudinal data, Optimizing Detection of True Within-Person Effects for Intensive Measurement Designs: A Comparison of Multilevel SEM and Unit-Weighted Scale Scores, https://doi.org/10.1023/B:JOBE.0000044735.51022.5d, https://doi.org/10.1037/0022-006X.49.2.193, https://doi.org/10.1177/001440290507100203, https://doi.org/10.1016/S0005-7894(75)80181-X, https://doi.org/10.1007/s40614-020-00263-x, https://doi.org/10.3758/s13428-011-0111-y, https://doi.org/10.1016/0005-7916(81)90055-0, http://creativecommons.org/licenses/by/4.0/, SI: Commentary on Slocum et al, Threats to Internal Validity. Correspondence to 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. 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. The key characteristic that maturational processes share is that they may produce behavioral changes that would be expected to accumulate as a function of elapsed time in the absence of participation in research.Footnote 2 In order to control for maturation, we must attend to the passage of timetypically, calendar days. Applied behavior analysis (3rd ed.). 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. 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. Timothy A. Slocum. https://doi.org/10.1002/bin.191, Article Behavioral Interventions, 20(3), 219224. The across-tier comparison is an additional basis for evaluating alternative explanations. A baseline (A) and an intervention (B) are included in a straightforward AB design psychological experiment (B). 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. 7. We use function of elapsed time descriptively rather than causally. Although the claims that nonconcurrent multiple baseline designs are weaker than concurrent multiple baselines, especially with respect to threats of coincidental events, are nearly universal in the current literature, none of these authors acknowledge or address, the arguments made by Watson and Workman (1981) and Hayes (1981) in support of these designs. Examples could include family events, illness, changed social interactions (e.g., breaking up with a partner), losing or gaining access to a social service program, etc. Kennedy, C.H. Routledge/Taylor & Francis Group. in their classic 1968 article that defined applied behavior analysis. The Nonconcurrent Multiple-Baseline Design: It is What it is and Not Something Else. Nonconcurrent designs are said to be substantially compromised with respect to internal validity and in general this limitation is ascribed to their supposed weakness in addressing threats of coincidental events (i.e., history). This is a preview of subscription content, access via your institution. One area that has, in the past, been particularly controversial is the experimental rigor of concurrent versus nonconcurrent multiple baseline designs; that is, the degree to which each can rule out threats to internal validity. Carr (2005) invokes this prediction, verification, and replication logic, and concludes, The nonconcurrent MB design only controls for threats associated with maturation/exposure; it does not control for historical [coincidental events] threats to internal validity, as does a concurrent MB design (p. 220). WebMultiple-Baseline Designs There are two potential problems with the reversal designboth of which have to do with the removal of the treatment. Controlling for maturation requires baseline phases of distinctly different temporal durations (i.e., number of days); controlling for testing and session experience requires baseline phases of substantially different number of sessions; and controlling for coincidental events requires phase changes on sufficiently offset calendar dates. Interrater agreement on the visual analysis of individual tiers and functional relations in multiple baseline designs. Second, in a remarkably understated reference to the across-tier comparison, Baer et al. (p. 325), Compared to its concurrent multiple baseline design sibling, a non-concurrent arrangement is inherently weaker . 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. Independent from Watson and Workman (1981), Hayes (1981) published a lengthy article introducing SCDs to clinical psychologists and made the point that these designs are well-suited to conducting research in clinical practice. In the case of multiple baseline designs, a stable baseline supports a strong prediction that the data path would continue on the same trajectory in the absence of an effective treatment; these predictions are said to be verified by observing no change in trajectories of data in other tiers that are not subjected to treatment; and replication is demonstrated when a treatment effect is seen in multiple tiers. (p. 206). https://doi.org/10.1023/B:JOBE.0000044735.51022.5d, Hayes, S. C. (1981). We will explore these issues extensively after we sketch the historical development of multiple baseline designs and criticisms of nonconcurrent multiple baselines. First, the design assumes that treatment effects will be tier-specific and not spread to untreated tiers. Consequently, it is often difficult or impossible to dismiss rival hypotheses or explanations. Likewise, setting-level coincidental events are those that contact a single setting. 2023 Springer Nature Switzerland AG. If either of these assumptions are not valid for a coincidental event, then the presence and function of that event would not be revealed by the across-tier analysis. Under the proposed definition, such a study would not be considered a full-fledged multiple baseline. 66 : Discuss the advantages and disadvantages of using visual inspection of graphs rather than statistics to evaluate the significance of the results. This comparison may reveal a likely maturation effect. Because experimental circumstances and design elements vary so greatly, no universal answer can be given. A multiple baseline design with tiers conducted at different times during each day could show disruption due to this coincidental event in the tier assessed early in the day but not in tiers that are assessed later in the day. Although it is plausible that an extraneous variables influence could coincide with one phase change, it is less plausible that such a coincidence would occur twice, and even less plausible that it would occur three times. The lag between phase changes must be long enough that maturation over any single amount of time cannot explain the results in multiple tiers. This paper describes procedures for using these designs, Thus, the assumption that the coincidental event contacts all tiers would be valid and the across-tier analysis might reveal the effects of this sort of event. 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. Perspect Behav Sci 45, 647650 (2022). Rather, the passage of time allows for more opportunities for participants to interact with their environmentleading to maturational changes. This has been the sharpest point of criticism of nonconcurrent multiple baselines. WebWhat are some disadvantages of alternating treatment design? Department of Educational Psychology, Neag School of Education, University of Connecticut, Storrs, CT, 06269, USA, You can also search for this author in 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. Smith, J. D. (2012). Single case experimental design and empirical clinical practice. Wacker, D., Berg, W., Harding, J., & Cooper-Brown, L. (2004). However, in a concurrent multiple baseline across participants, participant-level events contact only a single tier (participant)the coincidental event would not contact other tiers (participants)we might say that the across-tier analysis is inherently insensitive to detecting this kind of event. Advantages and Disadvantages of ABA Design. Maturational changes may be smooth and gradual, or they may be sudden and uneven. Given this dilemma, priority should be given to optimizing the within-tier comparisons because this is the comparison that can confer stronger control. Baer, D. M., Wolf, M. M., & Risley, T. R. (1968). 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. WebOften creates lots of problems BAB Reversal Design Doesnt enable assessment of effects prior to the intervention May get sequence effects May be appropriate with dangerous behaviors Addresses ethics of withholding effective treatment Need to be careful when using NCR Reversal Technique Noncontingent reversal Finally, practitioners whose work may be influenced by SCD research must understand these issues so they can give appropriate weight to research findings. 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. In this article, we argue that the primary reliance on across-tier comparisons and the resulting deprecation of nonconcurrent designs are not well-justified. This would draw attention to the relationship between the prediction from baseline and the (possible) contradiction of that prediction by the obtained treatment-phase data, and the replication of this prediction-contradiction pair in subsequent tiers. B. 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. Google Scholar. An example of multiple baseline across behaviors might be to use feedback to develop a comprehensive exercise program that involves stretching, aerobic exercise, They describe the control afforded by the design: The experimenter is assured that his treatment variable is effective when a change in rate appears after its application while the rate of concurrent (untreated) behaviors remains relatively constant (p. 226).
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