multiple baseline design disadvantages

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). 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. 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). This comparison can reveal the influence of an extraneous variable only if it causes a change in several tiers at about the same time. However, we can never ensure that any two contexts or any two session times are not subject to unique events during the study. the effects of the treatment variable are inferred from the untreated behaviors (p. 227). These events would contact all tiers of a MB that take place in that single setting, but not tiers in other settings. In this design, behavior is measured across either multiple individuals, behaviors, or settings. Table 1 summarizes these threats to internal validity and the dimension of lag necessary to control for each. Therefore, researchers must exercise extreme caution in interpreting and generalizing the results from pre-experimental studies. Characteristics of single-case designs used to assess intervention effects in 2008. This critical requirement is mainly addressed by the lag between phase changes in successive phases. Behavior Therapy, 6(5), 601608. 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. The logic of replicated within-tier analysis applies equally to concurrent and nonconcurrent designs. 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. Strategies and tactics of behavioral research and practice (4th ed.). (1981). 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. Second, the across-tier comparison assumes that extraneous variables will affect multiple tiers similarly. Still, for a given study, the results influence the number to tiers required in a rigorous multiple baseline design. If we observe a potential treatment effect in one tier and corresponding changes in untreated tiers after similar amounts of time (i.e., number of days), maturation becomes a more plausible alternative explanation of the initial potential treatment effect. A potential treatment effect in any single tier could plausibly be explained as a result of a coincidental event. 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.

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