Kazdin, A. E. (2021). 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). Ten sessions of baseline would be expected to have similar effects whether they occur in January or June. 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. The issue of concurrence of tiers should be considered along with many other design variations that can be manipulated to create a design that fits the particular experimental challenges of a particular study. Given this dilemma, priority should be given to optimizing the within-tier comparisons because this is the comparison that can confer stronger control. 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. The Nonconcurrent Multiple-Baseline Design: It is What it is and Not Something Else. WebExtended baselines or interventions may threaten experimental control, delayed intervention may pose a risk to client or others as an ethical concern. 2023 Springer Nature Switzerland AG. As a result, concurrent and nonconcurrent designs are virtually identical in their control for maturation threats. They then describe the multiple baseline technique (p. 94) and two types of comparisons that contribute to its experimental control. We challenge this assertion. When conditions are less ideal, additional tiers may be necessary. Experimental and quasi-experimental designs for research. Second, the across-tier comparison assumes that extraneous variables will affect multiple tiers similarly. WebAnother limitation cited for single-subject designs is related to testing. 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. Predi Abab Design Essay 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. These coincidental events would contact all tiers of a multiple baseline that include this individual participant, but not tiers that do not involve this participant. If this requirement is not met and a single extraneous event could explain the pattern of data in multiple tiers, then replications of the within-tier comparison do not rule out threats to internal validity as strongly. 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. . 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). If it changes at that point, evidence is accruing that the experimental variable is indeed effective, and that the prior change was not simply a matter of coincidence (p. 94). Finally, practitioners whose work may be influenced by SCD research must understand these issues so they can give appropriate weight to research findings. Likewise, in a multiple baseline across settings, selecting settings that tend to share extraneous events would make the across-tier analysis more powerful than would selecting settings that share few common events. 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. Single case experimental designs: Strategies for studying behavior change (3rd ed.). Harvey, M. T., May, M. E., & Kennedy, C. H. (2004). 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. https://doi.org/10.1016/0005-7916(81)90055-0, Wolfe, K., Seaman, M. A., & Drasgow, E. (2016). This insensitivity is not due to poor experimental design or implementation, it is built in to the nature of multiple baseline designs across participants. Journal of Consulting & Clinical Psychology, 49(2), 193211. B. Second, in a remarkably understated reference to the across-tier comparison, Baer et al.
10.2 Single-Subject Research Designs 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). Campbell, D. T., & Stanley, J. C. (1963).
Multiple-Baseline Design: Definition & Examples A given period of maturation may affect various participants, various behaviors, or behaviors in various settings in different ways. The across-tier analysis can provide an additional set of comparisons that may reveal a maturation effect, but it is not a conclusive test.
Small n Designs: ABA & Multiple-Baseline Designs 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). In this case, the effects of this kind of event could be revealed through the across-tier comparison of participants or behaviors that have not been exposed to the independent variable. 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. volume45,pages 619638 (2022)Cite this article. Multiple baseline designs are the workhorses of single-case design (SCD) research and are the predominant design used in modern applied behavior analytic research (Coon & Rapp, 2018; Cooper et al., 2020). Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Chapter 8 Multiple Baseline Designs - Florida Multiple baseline designs are intended to evaluate whether there is a functional (causal) relation between the introduction of the independent variable and changes in the dependent variable. Multiple baseline procedure.
Single-Subject Research Designs Research Methods in All three of these dimensions of lag are necessary to rigorously control for commonly recognized threats to internal validity and establish experimental control. Perspectives on Behavior Science Article (1981). Testing and session exposure may be particularly troublesome in a study that requires taking the participant to an unusual location and exposing them to unusual assessment situations in order to obtain baseline data.
National Center for Biotechnology Information . 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. Google Scholar. For example, physical growth and experiences with the environment can accumulate and result in relatively sudden behavioral changes when a toddler begins to walk. and (2) Was any change the result of the independent variable?
Ab design advantages simple to use It is possible that a coincidental event may be present for all tiers but have different effects on different tiers. 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). If a potential treatment effect is seen in one tier and on the same day there is no change in other tiers, this is taken as strong evidence that the potential treatment effect was not a result of a coincidental event, because a coincidental event would have had an effect on all tiers.
multiple baseline design 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 This critical requirement is mainly addressed by the lag between phase changes in successive phases. A researcher who puts great confidence in the across-tier comparison could falsely reject the idea that coincidental events were the cause of observed effects. 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. In such an instance, there may be a disruption to experimental control in only one-tier of the design and not others, thus influencing the degree of internal First, studies differ with respect to the experimental challenges imposed by the phenomena under study. 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. Craig H. Kennedy. 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). (1973). PubMed Central Under the proposed definition, such a study would not be considered a full-fledged multiple baseline. Rather, the passage of time allows for more opportunities for participants to interact with their environmentleading to maturational changes. However, an across-tier comparison is not definitive because testing or session experience could affect the tiers differently. In order to meet the terms of the definition, and confirm the critical characteristics for controlling threats to internal validity, we recommend that all multiple baseline studies explicitly report, for each tier, the number of days and sessions in each phase, and the number of calendar days of phase change lag from the previous tier. Journal of Behavior Therapy & Experimental Psychiatry, 12(3), 257259. For example, in a study of language skills in typically developing 3-year-old children, maturation would be a particular concern. The lag between phase changes must be long enough that maturation over any single amount of time cannot explain the results in multiple tiers. 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.
Chapter 14 quiz 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. 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. 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. Without the latter you cannot conclude, with confidence, that the intervention alone is responsible for observed behavior changes since baseline (or probe) data are not concurrently collected on all tiers from the start of the investigation. Control for testing and session experience requires attention to the number of sessions that participants experience. (Similar arguments can be made for comparisons across settings, persons, and other variables that might define tiers.) WebThe first quality of ideal baseline data is stability, meaning that they display limited variability. Smith, J. D. (2012). 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. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.
New Mexico's Flagship University | The University of New 288335). Create the data table in Sheets; 2. The multiple baseline design is useful for interventions that are irreversible due to learning effects, and when treatment cant be withdrawn. We are not pointing to flaws in execution of the design; we are pointing to inherent weaknesses. Journal of Consulting & Clinical Psychology, 49(2), 193211. 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. 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. Google Scholar. 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. 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. 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. The within-tier comparison may be further strengthened by increasing independence of the tier in other dimensions. The process begins with a simple baseline-treatment (AB) comparisona change from baseline to treatment within a single tier. This is consistent with the judgements made by numerous existing standards and recommendations (e.g., Gast et al., 2018; Horner et al., 2005; Kazdin, 2021; Kratochwill et al., 2013). 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. Finally, we make recommendations for more rigorous use, reporting, and evaluation of multiple baseline designs. 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.