Other threats to internal validity such as (1) ambiguous temporal precedence, (2) selection, (3) regression, (4) attrition, and (5) instrumentation are addressed primarily through other design features. For example, in a multiple baseline across settings, the settings could present somewhat different demands. Pergamon. Routledge. Experimental and quasi-experimental designs for research. Webmultiple baseline (3 forms) 1. across bx 2. across settings, 3. across subjects or groups using 3-5 tiers. 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. For example, instrumentation is addressed primarily through observer training, calibration, and IOA. Characteristics of single-case designs used to assess intervention effects in 2008. Without these dimensions of lag explicitly stated in the definition, we cannot claim that multiple baseline designs will necessarily include the features required to establish experimental control. Routledge/Taylor & Francis Group. 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. And researchers generally design and implement interventions, select tiers, and employ measures that will likely show consistent treatment effects. volume45,pages 619638 (2022)Cite this article. Book (2018) state: Confidence that maturation and history [coincidental events] threats are under control is based on observing (a) an immediate change in the dependent variable upon introduction of the independent variable, and (b) baseline (or probe) condition levels remaining stable while other tiers are exposed to the intervention. 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. We use the term potential treatment effect to emphasize that the evidence provided by this single AB within-tier comparison is not sufficient to draw a strong causal conclusion because many threats to internal validity may be plausible alternative explanations for the data patterns. In general, a longer lag is better because it reduces the chance that an event could impact multiple tiers. The assumption that all tiers respond similarly to maturation may be somewhat more problematic. 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. To summarize, the replicated within-tier analysis with sufficient lag can rigorously control for the threat of maturation. 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. 66 : Discuss the advantages and disadvantages of using visual inspection of graphs rather than statistics to evaluate the significance of the results. Google Scholar, Gast, D. L., Lloyd, B. P., & Ledford, J. R. (2018). Data analysis issues concern two closely related questions: (1) Was there a change in data patterns after the phase change? 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. In this case, the across-tier comparison would give the false appearance of strong internal validity. https://doi.org/10.1016/0005-7916(81)90055-0, Wolfe, K., Seaman, M. A., & Drasgow, E. (2016). Multiple Therefore, we view this approach as less desirable than the standard multiple baseline design across subjects and suggest that it should be employed only when the standard approach is not feasible. Consequently, it is often difficult or impossible to dismiss rival hypotheses or explanations. (Similar arguments can be made for comparisons across settings, persons, and other variables that might define tiers.) Watson and Workman did not explicitly address threats to internal validity other than coincidental events. They argue that because nonconcurrent multiple baseline designs lack an across-tier comparison in real time (the criticism described above), they cannot verify the prediction of the behavior pattern in the absences of intervention. Adding multiple tiers to the design allows for two types of additional comparisons to be used to evaluate, and perhaps rule out, these threats: (1) replications of baseline-treatment comparisons within subsequent tiers (i.e., horizontal analysis), and (2) comparisons across tiers (i.e., vertical analysis). 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). This is a preview of subscription content, access via your institution. 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. 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. Part of Springer Nature. Provided by the Springer Nature SharedIt content-sharing initiative, Over 10 million scientific documents at your fingertips, Not logged in If an effective treatment were to have a broad impact on multiple tiers, the logic of the design would be to falsely attribute these effects to possible extraneous variables. The logic of replicated within-tier analysis applies equally to concurrent and nonconcurrent designs. 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. 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). The Nonconcurrent Multiple-Baseline Design: It is What it Kennedy, C. H. (2005). 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. 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. Journal of Behavioral Education, 13, 267276. They do not elaborate on the importance of this type of comparison. https://doi.org/10.1016/S0005-7894(75)80181-X, Kratochwill, T. R., Hitchcock, J., Horner, R. H., Levin, J. R., Odom, S. L., Rindskopf, D. M., & Shadish, W. R. (2013). 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. Potential setting-level events include staffing changes in classroom, redecoration or renovation of the physical environment, and changes in the composition of the peer group in a classroom, group home, or worksite. However, if this within-tier pattern is replicated in multiple tiers after differing numbers of baseline sessions, this threat becomes increasingly implausible. Single case experimental design and empirical clinical practice. (1968) who emphasized the replicated within-tier comparison. 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). 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. Coincidental events share the characteristic that their behavioral impact is expected to be a function of particular dates. A : true B : false. We will explore these issues extensively after we sketch the historical development of multiple baseline designs and criticisms of nonconcurrent multiple baselines. 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. 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). This statement, of course, fails to satisfy the operational desire for a specific number of tiers that accomplishes this function. https://doi.org/10.1002/bin.191, Article Book In this article, we first define multiple baseline designs, describe common threats to internal validity, and delineate the two bases for controlling these threats. Interrater agreement on the visual analysis of individual tiers and functional relations in multiple baseline designs. Journal of Applied Behavior Analysis, 1(1), 9197. Natural multiple baselines across persons: A reply to Harris and Jenson. Type I Errors and Power in Multiple Baseline Designs, Assessing consistency of effects when applying multilevel models to single-case data. 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). 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. Creating Single-Subject Research Design Graphs If a nonconcurrent multiple baseline has a long lag in real time between phase changes (e.g., weeks or months), this may provide stronger control than a design with a lag of one or several days. (Our specification of phase change offset in terms of real time, days in baseline, and sessions in baseline is unusual. 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]. Threats to Internal Validity in Multiple-Baseline Design https://doi.org/10.1023/B:JOBE.0000044735.51022.5d, Hayes, S. C. (1981). Single-case experimental designs: A systematic review of published research and current standards. In concurrent multiple baseline across participants, behaviors, or stimulus materials that take place in a single setting, this kind of event would contact all the tiers of the multiple baseline. WebDisadvantages to Multiple Baseline Designs -Weaker method of showing experimental control than a reversal (b/c no withdrawal of treatment) -Delay in treatment can occur as Although many maturational changes are gradual, more sudden changes are possible. Only through repeated measurement across all tiers from the start of a study can you be confident that maturation and history threats are not influencing observed outcomes. https://doi.org/10.1007/s40614-022-00343-0, SI: Commentary on Slocum et al, Threats to Internal Validity. Journal of Applied Behavior Analysis, 30(3), 533544. Psychological Methods, 17(4), 510550. https://doi.org/10.1007/s40614-020-00263-x, Shadish, W. R., & Sullivan, K. J. Barlow, D. H., Nock, M. K., & Hersen, M. (2009). Multiple baseline and changing criterion design Flashcards Slider with three articles shown per slide. The time lag must be sufficiently long so that no single event could produce potential treatment effects in more than one tier. https://doi.org/10.1002/bin.1510. The process begins with a simple baseline-treatment (AB) comparisona change from baseline to treatment within a single tier. Cooper, J. O., Heron, T. E., & Heward, W. L. (2020). 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. 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. PubMed Central 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. 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. Hersen, M., & Barlow, D. H. (1976). The lag between phase changes must be long enough that maturation over any single amount of time cannot explain the results in multiple tiers. Addressing the second question requires data analysis that is informed by the specifics of the study. WebA multiple baseline design across behaviors was used to examine intervention effects. Perspectives on Behavior Science, 43, 605616. That is, it is not strong evidence verifying the prediction of no change in the initial tier in the absence of an intervention. Disadvantages A potential treatment effect in any single tier could plausibly be explained as a result of a coincidental event. They never raise the question of whether replicated within-tier comparisons are sufficient to rule out threats to internal validity and establish experimental control. Thus, to the degree that nonconcurrent designs support longer lags between phases changes than concurrent designs, they may support stronger control of the threat of coincidental events through replicated within-tier comparisons. This skepticism of nonconcurrent designs stems from an emphasis on the importance of across-tier comparisons and relatively low importance placed on replicated within-tier comparisons for addressing threats to internal validity and establishing experimental control. 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. Journal of Behavior Therapy & Experimental Psychiatry, 12(3), 257259. They state, the nonconcurrent multiple baseline across participants design is inherently weaker than other multiple baseline design variations. Alternating Treatment Designs Watch on What are the disadvantages of alternating treatments? 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. 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). Campbell, D. T., & Stanley, J. C. (1963). This assumption was initially identified by Kazdin and Kopel in 1975, but its implications for the rigor of the across-tier comparison have rarely been discussed since that time. In order to demonstrate experimental control, the researcher makes two paradoxical assumptions. The vast majority of contemporary published multiple baseline designs describe the timing of phases in terms of sessions rather than days or dates. (2022), Revisiting an Analysis of Threats to Internal Validity in Multiple Baseline Designs, Moderation analysis in two-instance repeated measures designs: Probing methods and multiple moderator models, Examining and Enhancing the Methodological Quality of Nonconcurrent Multiple-Baseline Designs, How Many Tiers Do We Need? However, we can never ensure that any two contexts or any two session times are not subject to unique events during the study. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. Other design features that contribute to the isolation of tiers such that any single extraneous variable is unlikely to contact multiple tiers can also strengthen the independence of tiers. Single-Subject Research Designs Research Methods in This controversy began soon after the first formal description of nonconcurrent multiple baseline designs by Hayes (1981) and Watson and Workman (1981). the effects of the treatment variable are inferred from the untreated behaviors (p. 227). Part of Springer Nature. Each tier involves a unique participant and there is a class of coincidental events that contact a single participant. The across-tier comparison of concurrent multiple baseline designs is less certain and definitive than it may appear. 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. The across-tier comparison provides another possible source of control for maturation. For example, there is less room for participant-level coincidental events if all participants reside in a single group home than if they reside in different group homes in different states. 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 Chapter 8 Multiple Baseline Designs - Florida However, each replication of the possible treatment effect that takes place at a substantially distinct calendar date reduces the plausibility of this threat. That is, session numbers do not necessarily correspond to the same periods of real time across tiers. The general steps for the development of the line graphs are as follows: 1. National Center for Biotechnology Information 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. 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. 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. A coincidental event may contact a single unit of analysis (e.g., one of four participants) or multiple units (e.g., all participants). 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 In the past, there was significant controversy regarding the relative rigor of concurrent and nonconcurrent multiple baseline designs. 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. Web14 : A multiple-baseline design requires that the targeted behavior return to baseline levels when the treatment is removed. (1981). It is surprising that there is no single consensus definition of multiple baseline designs. An important drawback of pre-experimental designs is that they are subject to numerous threats to their validity. 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. 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. Further, for both types of multiple baselines, the threat of coincidental events should be evaluated primarily based on replicated within-tier comparisons. For example, in a study of language skills in typically developing 3-year-old children, maturation would be a particular concern. Perspectives on Behavior Science 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. Baer, D. M., Wolf, M. M., & Risley, T. R. (1968). - 181.212.136.34. 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. Google Scholar. multiple baseline design 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 This paper describes procedures for using these designs, It is clear that we cannot claim that these assumptions are always valid for multiple baseline designs. The present article is focused on the second questionwhether systematic changes in data can be attributed to the treatment. Pearson. We can identify at least three general categories of issues that influence the number of tiers required to render threats implausible: challenges associated with the phenomena under study, experimental design features, and data analysis issues. Sidman, M. (1960). How many tiers do we need? With stable data, the range within which future data points will fall is We have no known conflict of interest to disclose. 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. Single-case research designs: Methods for clinical and applied settings (3rd ed.). In this design, behavior is measured across either multiple individuals, behaviors, or settings. Multiple baseline designs can rigorously control these threats to internal validity. 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. Experimental and quasi-experimental designs for generalized causal inference. 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. https://doi.org/10.1177/001440290507100203, Johnston, J. M., Pennypacker, H. S., & Green, G. (2020). WebGive two advantages and two disadvantages of quasi-experimental designs. Reversal Designs - University of Idaho Google Scholar. Reasons for these specifications will become clear later in the article.) Coincidental events (i.e., history) are specific events that occur at a particular time (or across a particular period) and could cause changes in behavior. This comparison can reveal the influence of an extraneous variable only if it causes a change in several tiers at about the same time. Recognizing these three dimensions of lag has implications for reporting multiple baseline designs. The within-tier comparison may be further strengthened by increasing independence of the tier in other dimensions. Events that contact a single participant may be termed participant-level. Additionally, the In addition, arranging tiers that are isolated in other dimensions (e.g., location, behaviors, participants) confers overall strength, not weakness, for addressing coincidental events. Behavioral cusps: A developmental and pragmatic concept for behavior analysis. This comparison may reveal a likely maturation effect. 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. Recommendations for reporting multiple-baseline designs across participants. Longer lags and more isolated tiers can reduce the number of tiers necessary to render extraneous variables implausible explanations of results. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. 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. 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. WebThe first quality of ideal baseline data is stability, meaning that they display limited variability. WebThe main disadvantage of the multiple baseline design is that a high degree of planning is required to produce a successful implementation. 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. Maturational changes may be smooth and gradual, or they may be sudden and uneven. Data from the treatment phase in one tier can be compared to corresponding baseline data in another tier. So, for example, session 10 in tier 2 must take place at some time between tier 1s session 9 and 11. They do not mention the across-tier comparison, presumably because they believe that this analysis is not necessary to establish experimental control. Single case experimental designs: Strategies for studying behavior change (3rd ed.). We use function of elapsed time descriptively rather than causally. That is, experimental control has not been convincingly demonstrated. Carr, J. E. (2005). disadvantages The multiple baseline family of designs includes multiple baseline and multiple probe designs. This pattern seriously weakens the argument that the independent variable was responsible for the change in the treated tier. https://doi.org/10.1037/0022-006X.49.2.193. Nonconcurrent multiple baseline designs for educational program evaluation. Some researchers believe ABAB is a stronger design since it has multiple reversals. Oxford. These reports do not provide the information necessary to rigorously evaluate maturation or coincidental events. One is that if a Behavioral Assessment, 7(2), 129132. Multiple Baseline Flashcards | Quizlet
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