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. Poor execution can certainly worsen these problems, but good execution cannot eliminate them. 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. They never raise the question of whether replicated within-tier comparisons are sufficient to rule out threats to internal validity and establish experimental control. Watson and Workman did not explicitly address threats to internal validity other than coincidental events. Describe the retrospective and prospective research designs. Routledge. Throughout this article we have referred to the importance of replicating within-tier comparisons, emphasizing the idea that tiers must be arranged with sufficient lag in phase changes so that specific threats to internal validity are logically ruled out. We challenge this assertion. Pearson. 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 Provided by the Springer Nature SharedIt content-sharing initiative, Over 10 million scientific documents at your fingertips, Not logged in WebDisadvantage: Covariance among subjects may emerge if individuals learn vicariously through the experiences of other subjects Also, identifying multiple subjects in the same Coincidental events share the characteristic that their behavioral impact is expected to be a function of particular dates. 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. Routledge/Taylor & Francis Group. 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). Learn more about Institutional subscriptions. It is surprising that there is no single consensus definition of multiple baseline 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. Design Further, if the potential treatment effect is more gradual (as one might expect from an educational intervention on a complex skill), maturational changes may be impossible to distinguish from treatment effects. This comparison can reveal the influence of an extraneous variable only if it causes a change in several tiers at about the same time. 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 This controversy began soon after the first formal description of nonconcurrent multiple baseline designs by Hayes (1981) and Watson and Workman (1981). The functional answer to this question is that there must be sufficient tiers so that none of the threats to internal validity are plausible explanations for the pattern of effects across the set of tiers. 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. PubMed Central In addition, functionally isolating tiers (e.g., across settings) such that they are highly unlikely to be subjected to the same instances of a threat can also contribute to this goal. The within-tier comparison may be further strengthened by increasing independence of the tier in other dimensions. 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. The multiple baseline design was initially described by Baer et al. Any of these types of circumstances may require additional tiers in order to clearly address threats to internal validity. 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). Google Scholar. Behavioral Assessment, 7(2), 129132. For example, in a multiple baseline across participants, all the residents of a group home may contact peanut butter and jelly sandwiches for lunch but this change may disrupt the behavior of residents with a mild peanut allergy, but not other residents. That is, experimental control has not been convincingly demonstrated. WebExtended baselines or interventions may threaten experimental control, delayed intervention may pose a risk to client or others as an ethical concern. Single-case intervention research design standards. 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. The use of single-subject research to identify evidence-based practice in special education. Using Single-Case Designs in Practical Settings: Is Within-Subject Replication Always Necessary? 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. 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). A coincidental event may contact a single unit of analysis (e.g., one of four participants) or multiple units (e.g., all participants). Strategies and tactics of behavioral research and practice (4th ed.). 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 vast majority of contemporary published multiple baseline designs describe the timing of phases in terms of sessions rather than days or dates. If, in the initial tier, a pattern of stable baseline data is followed by a distinct change soon after the phase change, this constitutes a potential treatment effect. 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). 288335). Book The bottom line is that the experimenter can never know whether a coincidental event has contacted only a single tier of a concurrent multiple baseline and, therefore, whether it is possible for the across-tier comparison to detect this threat. Behavior Research Methods, 43(4), 971980. https://doi.org/10.1007/s40614-022-00326-1, DOI: https://doi.org/10.1007/s40614-022-00326-1. A functional relation can be inferred if the pattern of data demonstrates experimental controlthe experimenters ability to produce a change in the dependent variable in a precise and reliable fashion (Sidman, 1960). It would be an even greater concern if the treatment were an instructional program that requires several weeks or months to implement.