multiple baseline design disadvantages

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. https://doi.org/10.1177/0741932512452794, Lanovaz, M. J., & Turgeon, S. (2020). This information would allow readers to evaluate the sufficiency of each dimension of lag given the specific characteristics of the particular study. 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. 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. 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. To summarize, the replicated within-tier analysis with sufficient lag can rigorously control for the threat of maturation. 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. The ABA or Reversal 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 This comparison can reveal the influence of an extraneous variable only if it causes a change in several tiers at about the same time. 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. 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. Elapsed time does not directly cause maturational changes in behavior. 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. If factors other than the experimenters manipulation of the independent variable could plausibly account for the obtained data patterns, experimental control has not been demonstrated and functional relations cannot be inferred. In addition, multiple baseline designs are increasingly used in literatures that are not explicitly behavior analytic. WebMultiple-Baseline Designs There are two potential problems with the reversal designboth of which have to do with the removal of the treatment. Routledge. On the other hand, if we observe that one tier shows a change whereas other tiers that have been observed for similar amounts of time do not show similar changes, this may reduce the plausibility of the maturation threat. PubMedGoogle Scholar. Finally, we make recommendations for more rigorous use, reporting, and evaluation of multiple baseline designs. The across-tier comparison is an additional basis for evaluating alternative explanations. Thus, the additional temporal separation that is possible in a nonconcurrent design is a strength rather than a weakness in controlling for coincidental events. Part of Springer Nature. Ten sessions of baseline would be expected to have similar effects whether they occur in January or June. https://doi.org/10.1002/bin.191, Article 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. Predi Abab Design Essay (2020) make a somewhat different methodological criticism of nonconcurrent multiple baseline designs. (1973). This is a significant problem for the across-tier comparison because its logic is dependent on these two assumptions. Journal of Behavioral Education, 13(4), 213226. Events that contact a single participant may be termed participant-level. Later they present an overall evaluation of the strength of multiple baseline designs, attributing its primary weakness to its reliance on the across-tier comparison, The multiple baseline design is considerably weaker than the withdrawal design as the controlling effects of the treatment on each of the target behaviors is not directly demonstrated . The author has no known conflicts of interest to disclose. 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. Sometimes, the multiple baseline design may be more appropriate to use in interventions with small sample 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. 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. This argument rests on the assumptions that any extraneous variable that affects one tier will (1) contact all tiers and (2) have a similar effect on all tiers. . In addition, arranging tiers that are isolated in other dimensions (e.g., location, behaviors, participants) confers overall strength, not weakness, for addressing coincidental events. Book According to conventional wisdom, concurrent multiple baselines are superior because they allow for across-tier comparisons that can rule out coincidental events. WebA multiple baseline design across behaviors was used to examine intervention effects. In this section, we examine how within- and across-tier comparisons may support (or fail to support), internal validity in concurrent and nonconcurrent multiple baseline designs. In this case, the across-tier comparison would give the false appearance of strong internal validity. 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. 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. Some researchers believe ABAB is a stronger design since it has multiple reversals. 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. This pattern seriously weakens the argument that the independent variable was responsible for the change in the treated tier. In general, a longer lag is better because it reduces the chance that an event could impact multiple tiers. Using Single-Case Designs in Practical Settings: Is Within-Subject Replication Always Necessary? The lack of change in untreated tiers should be interpreted only as weak evidence supporting internal validity given the plausible alternative explanations of this lack of change. (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. Routledge/Taylor & Francis Group. Correspondence to For example, phase changes in two consecutive tiers may be lagged by three sessions, but if one to three sessions are conducted per day, the baseline phases could include the same number of days (problem for controlling maturation) and the phase change could occur on the same day in both tiers (problem for controlling coincidental events). Behavioral Assessment, 7(2), 129132. 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. The lag between phase changes must be long enough that maturation over any single amount of time cannot explain the results in multiple tiers. WebAnother limitation cited for single-subject designs is related to testing. (Our specification of phase change offset in terms of real time, days in baseline, and sessions in baseline is unusual. write that after implementing the treatment in an initial tier, the experimenter perhaps notes little or no change in the other baselines (p. 94). The vast majority of contemporary published multiple baseline designs describe the timing of phases in terms of sessions rather than days or dates. This controversy began soon after the first formal description of nonconcurrent multiple baseline designs by Hayes (1981) and Watson and Workman (1981). Exceptional Children, 71, 165179. The multiple baseline design was initially described by Baer et al. Throughout their discussion of SCD, these authors describe experimental control in terms of three processes: prediction, verification, and replication. Consequently, it is often difficult or impossible to dismiss rival hypotheses or explanations. In general, in a concurrent multiple baseline design across any factor, the across-tier analysis is inherently insensitive to coincidental events that are limited to a single tier of that factor. Recommendations for reporting multiple-baseline designs across participants. 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. 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. WebNew Mexico's Flagship University | The University of New Mexico 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. 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. Behavior Research Methods, 43(4), 971980. Oxford University Press. Likewise, setting-level coincidental events are those that contact a single setting. 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. Pearson Education. 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. We are not pointing to flaws in execution of the design; we are pointing to inherent weaknesses. - 216.238.99.111. https://doi.org/10.4324/9781315150666, Chapter 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. Perspect Behav Sci 45, 619638 (2022). Johnston, J. M., Pennypacker, H. S., & Green, G. (2010). Each replication requires an assumption of a separate event coinciding with a distinct phase change. It is interesting that this emphasis on across-tier comparisons is the opposite of that evident in Baer et al. https://doi.org/10.4324/9781315537085. Kazdin and Kopel (1975) parallel much of Hersen and Barlows (1976) commentaryFootnote 3 but they also point out an apparent contradiction in the assumptions about behavior on which the multiple baseline design is built. Concurrent multiple baseline designs are multiple baseline designs in which the tiers are synchronized in real time. This would align the definition with the critical features required to demonstrate experimental control and thereby allow strong causal statements based on multiple baseline designs. Journal of Applied Behavior Analysis, 1(1), 9197. Control for testing and session experience requires attention to the number of sessions that participants experience. Multiple baseline and multiple probe designs. A baseline (A) and an intervention (B) are included in a straightforward AB design psychological experiment (B). This has been the sharpest point of criticism of nonconcurrent multiple baselines. PubMedGoogle Scholar. In the past, there was significant controversy regarding the relative rigor of concurrent and nonconcurrent multiple baseline designs. However, it does not rule out maturation as an alternative explanation of the change in behavior. The problem of tier-specific coincidental events can be reduced by selecting tiers that differ on only a single factor (e.g., participants, settings, behaviors) and are as similar as possible on that factor. https://doi.org/10.1177/001440290507100203, Johnston, J. M., Pennypacker, H. S., & Green, G. (2020). That is, it is not strong evidence verifying the prediction of no change in the initial tier in the absence of an intervention. When changes in data occur immediately after the phase change, are large in magnitude, and are consistent across tiers, threats to internal validity tend to be less plausible explanations of the data patterns, and fewer tiers would be required to rule them out. Peer reviewers and editors who serve as gatekeepers for the scientific literature must also have a deep understanding of these issues so that they can distinguish between stronger and weaker research, ensure that information critical to evaluating internal validity is included in research reports, and assess the appropriateness of discussion and interpretation of results. Strategies and tactics of behavioral research. Second, the across-tier comparison assumes that extraneous variables will affect multiple tiers similarly. These observations lead us to the conclusion that neither of the critical assumptions that coincidental events will (1) contact and (2) have similar impact on all tiers can be assumed to be valid. Poor execution can certainly worsen these problems, but good execution cannot eliminate them. Correspondence to PubMed Reasons for these specifications will become clear later in the article.) The assumption that all tiers respond similarly to maturation may be somewhat more problematic. Nonconcurrent multiple baseline designs for educational program evaluation. PubMed Central Rather, the passage of time allows for more opportunities for participants to interact with their environmentleading to maturational changes. Create the graph from the data in Sheets; 3. 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. This question cannot be addressed by data analysis alone; any pattern of data, no matter how dramatic, could be a result of an extraneous variable if the experimental design features are not properly arranged. Three phonological patterns were targeted for each child. On the other hand, if we see a change in a treated tier and no change in untreated tiers, does this constitute strong evidence to rule out threats to internal validity? Hayes, S. C. (1981). Learn more about Institutional subscriptions. Coincidental events might be expected to be more variable in their effect than interventions that are designed to have consistent effects. These views of multiple baseline designs have been carried through into much of the single-case methodological literature and textbooks to the current day. As we mentioned above, across-tier comparisons require the assumptions that coincidental events will (1) contact and (2) have similar effects on all tiers of the design. The authors discuss two designs commonly used to demonstrate reliable control of an important behavior change (p. 94). WebThe main disadvantage of the multiple baseline design is that a high degree of planning is required to produce a successful implementation. Journal of Behavioral Education, 13, 267276. Timothy A. Slocum. https://doi.org/10.1007/s40614-022-00343-0, SI: Commentary on Slocum et al, Threats to Internal Validity. 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). The multiple baseline family of designs includes multiple baseline and multiple probe designs. Natural multiple baselines across persons: A reply to Harris and Jenson. Journal of Consulting & Clinical Psychology, 49(2), 193211. Having identified the criticisms of nonconcurrent multiple baseline designs, we now turn to a detailed analysis of threats to internal validity and features that can control these threats. 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. 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]. . Behavioral Interventions, 33(2), 160172. 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. Second, as we have discussed above, the amount of lag between phase changes (in terms of sessions in baseline, days in baseline, and elapsed days) is the primary design feature that reduces the plausibility of any single threat accounting for changes in multiple tiers, and thereby threatening the internal validity of the design as a whole. (Similar arguments can be made for comparisons across settings, persons, and other variables that might define tiers.) The point is that although the across-tier comparison may reveal a maturation effect, there are also circumstances in which it may fail to do so. We will focus on the three types of threats that are addressed through comparisons between baseline and treatment phases in multiple baseline designs: maturation, testing and session experience, and coincidental events.Footnote 1. Basic Books. 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.
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