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multiple baseline design disadvantages

    multiple baseline design disadvantages

    Finally, practitioners whose work may be influenced by SCD research must understand these issues so they can give appropriate weight to research findings. However, it does not rule out maturation as an alternative explanation of the change in behavior. In order to demonstrate experimental control, the researcher makes two paradoxical assumptions. WebMultiple Baseline Description Multiple measures are used to obtain data over two or more baselines The end result appears visually as a series of A-B designs on top of one another The DV may consist of 2 or more different behaviors Versatile and relatively easy to understand Perhaps the most common design in use today Multiple Baseline Design If Hayes, S. C. (1981). Carr, J. E. (2005). 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. Single-case experimental designs: A systematic review of published research and current standards. 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. Journal of Behavioral Education, 13(4), 213226. However, in a concurrent multiple baseline across participants, participant-level events contact only a single tier (participant)the coincidental event would not contact other tiers (participants)we might say that the across-tier analysis is inherently insensitive to detecting this kind of event. 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. 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. 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. We are not pointing to flaws in execution of the design; we are pointing to inherent weaknesses. WebExtended baselines or interventions may threaten experimental control, delayed intervention may pose a risk to client or others as an ethical concern. 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. 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. Routledge/Taylor & Francis Group. WebDisadvantage: Covariance among subjects may emerge if individuals learn vicariously through the experiences of other subjects Also, identifying multiple subjects in the same 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. If A changes after B is put into practice, a researcher can draw the Conclusion that B caused A to change. 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. Google Scholar. That is, it is not strong evidence verifying the prediction of no change in the initial tier in the absence of an intervention. In this highly influential early textbook on SCD, Hersen and Barlow describe only the across-tier analysis and fail to mention replicated within-tier comparisons. https://doi.org/10.1023/B:JOBE.0000044735.51022.5d, Hayes, S. C. (1981). 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. Strategies and tactics of behavioral research. Houghton Mifflin. https://doi.org/10.1007/s40614-022-00343-0, SI: Commentary on Slocum et al, Threats to Internal Validity. With stable data, the range within which future data points will fall is A given period of maturation may affect various participants, various behaviors, or behaviors in various settings in different ways. The strength of this control is a function of our certainty that no single coincidental event could have caused more than one change in the dependent variable. volume45,pages 647650 (2022)Cite this article. Tactics of scientific research. Concurrent and nonconcurrent multiple baseline designs address maturation in virtually identical ways through both within- and across-tier comparisons. In general, a longer lag is better because it reduces the chance that an event could impact multiple tiers. An important drawback of pre-experimental designs is that they are subject to numerous threats to their validity. The general steps for the development of the line graphs are as follows: 1. This information would allow readers to evaluate the sufficiency of each dimension of lag given the specific characteristics of the particular study. et al. Third, patterns of results influence the number of tiers needed to yield definitive conclusions. 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. 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. We recommend that multiple baseline design be defined as a single-case experimental design that evaluates causal relations through multiple baseline-treatment comparisons with phase changes that are sufficiently offset in (1) real time (i.e., calendar date), (2) number of days in baseline, and (3) number of sessions in baseline. 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. 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 . First, the design assumes that treatment effects will be tier-specific and not spread to untreated tiers. Testing and session experience encompasses features of experimental sessions (both baseline and intervention phases) other than the independent variable that could cause changes in behavior. Harvey, M. T., May, M. E., & Kennedy, C. H. (2004). https://doi.org/10.1901/jaba.1968.1-91, Article This statement, of course, fails to satisfy the operational desire for a specific number of tiers that accomplishes this function. Google Scholar. 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). Third, we explore how concurrent and nonconcurrent multiple baselines address each of the main threats to internal validity. Barlow, D. H., Nock, M. K., & Hersen, M. (2009). Reasons for these specifications will become clear later in the article.) Cooper et al. Webmultiple baseline (3 forms) 1. across bx 2. across settings, 3. across subjects or groups using 3-5 tiers. In J. R. Ledford & D. L. Gast (Eds. WebIn yet a third version of the multiple-baseline design, multiple baselines are established for the same participant but in different settings. Multiple baseline procedure. These events would contact all tiers of a MB that take place in that single setting, but not tiers in other settings. They never raise the question of whether replicated within-tier comparisons are sufficient to rule out threats to internal validity and establish experimental control. The within-tier analysis seeks replication of these potential treatment effects in additional tiers of the design. AB Design. This controversy began soon after the first formal description of nonconcurrent multiple baseline designs by Hayes (1981) and Watson and Workman (1981). Journal of Behavioral Education, 13(4), 267276. Second, in a remarkably understated reference to the across-tier comparison, Baer et al. 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. Book Recommendations for reporting multiple-baseline designs across participants. With control for coincidental events in multiple baseline designs resting squarely on replicated within-tier comparisons, there is no basis for claiming that, in general, concurrent designs are methodologically stronger than nonconcurrent designs. Single-case research designs: Methods for clinical and applied settings (3rd ed.). PubMed Central They then describe the multiple baseline technique (p. 94) and two types of comparisons that contribute to its experimental control. Sidman, M. (1960). Using Single-Case Designs in Practical Settings: Is Within-Subject Replication Always Necessary? Recognizing these three dimensions of lag has implications for reporting multiple baseline designs. 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. Provided by the Springer Nature SharedIt content-sharing initiative, Over 10 million scientific documents at your fingertips, Not logged in However, an across-tier comparison is not definitive because testing or session experience could affect the tiers differently. Natural multiple baselines across persons: A reply to Harris and Jenson. Part of Springer Nature. 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. Slocum, T.A., Pinkelman, S.E., Joslyn, P.R. 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). Thus, the assumption that the coincidental event contacts all tiers would be valid and the across-tier analysis might reveal the effects of this sort of event. 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. For example, knowing the date of session 10 in tier 1 tells us nothing about the date of session 10 in tier 2. Rather, the passage of time allows for more opportunities for participants to interact with their environmentleading to maturational changes. https://doi.org/10.1002/bin.191, Article . This is a preview of subscription content, access via your institution. Therefore, we believe that these features should be explicitly included in the definition of multiple baseline designs. 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. Craig H. Kennedy. 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. If a potential treatment effect is seen in one tier, the researcher cannot refer to data from the same day in an untreated tier because the tiers are not synchronized in real time and may not even overlap in real time. 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. In this design, behavior is measured across either multiple individuals, behaviors, or settings. WebAB design advantages - -simple to use AB design disadvantages - -cannot be used to make a confident assumption of a functional relation -vulnerable to confounding variables -does not provide for replication AB design - basic single subject design AB design has two phases of design - A: Baseline B: Intervention Reversal Design referred to as - 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. If session experience exerted a small degree of influence on the DV, an effect might be observed in settings where the behavior is more likely, but not in settings where the behavior is less likely. 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. Maturational changes may be smooth and gradual, or they may be sudden and uneven. 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. 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). Describe the retrospective and prospective research designs. By synchronized we mean that session 1 in all tiers takes place before session 2 in any tier, and this ordinal invariance of session number across tiers is true for all sessions. 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. Coincidental events share the characteristic that their behavioral impact is expected to be a function of particular dates. https://doi.org/10.1007/s40614-022-00326-1, DOI: https://doi.org/10.1007/s40614-022-00326-1. To summarize, the replicated within-tier analysis with sufficient lag can rigorously control for the threat of maturation. Journal of Applied Behavior Analysis, 30(3), 533544. That is, experimental control has not been convincingly demonstrated. In this article, we argue that the primary reliance on across-tier comparisons and the resulting deprecation of nonconcurrent designs are not well-justified. Data from the treatment phase in one tier can be compared to corresponding baseline data in another tier. When conditions are less ideal, additional tiers may be necessary. 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. 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, 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. 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. Type I errors and power in multiple baseline designs. 7. This has at least two effects: first, the multiple baseline is seen as weaker than the withdrawal design because of this dependence on the across-tier analysis; and second, when nonconcurrent multiple baseline designs are introduced years later, their rigor will be understood by many methodologists in terms of control by across-tier comparisons only, without consideration of replicated within-tier comparisons. Predi Abab Design Essay The Nonconcurrent Multiple-Baseline Design: It is What it is and Not Something Else. Hayes, S. C. (1985). The assumption that maturation contacted all tiers is strongparticipants were all exposed to maturational variables (i.e., unidentified biological events and environmental interactions) for the same amount of time. 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. Single case experimental designs: Strategies for studying behavior change (3rd ed.). 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). However, critics of nonconcurrent designs have rarely (1) made a thorough and critical analysis of the potential weaknesses of across-tier comparisons in concurrent multiple baselines, or (2) evaluated the degree of experimental control that can be demonstrated by replicated within-tier comparisons. https://doi.org/10.1177/001440290507100203, Johnston, J. M., Pennypacker, H. S., & Green, G. (2020). Three phonological patterns were targeted for each child. 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. Slider with three articles shown per slide. 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. Baer, D. M., Wolf, M. M., & Risley, T. R. (1968). Rand McNally. Perhaps a more general and powerful triad of processes that support demonstration of experimental control would be prediction, contradiction, and replication. 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. https://doi.org/10.3758/s13428-011-0111-y, Article WebNew Mexico's Flagship University | The University of New Mexico Thus, although the across-tier analysis does provide a test of the maturation threat, a lack of change in untreated tiers cannot definitively rule it out. 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 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. According to conventional wisdom, concurrent multiple baselines are superior because they allow for across-tier comparisons that can rule out coincidental events. We use function of elapsed time descriptively rather than causally. And researchers generally design and implement interventions, select tiers, and employ measures that will likely show consistent treatment effects. 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 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.

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