multiple baseline design disadvantages

a potential treatment effect in the first tier would be vulnerable to the threat that the changes in data could be a result of In addition, multiple baseline designs are increasingly used in literatures that are not explicitly behavior analytic. So, similar to maturation, the across-tier comparison is sometimes able to reveal effects of testing and session experience, but it may fail to do so in some circumstances. 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. Cooper et al. 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. 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. First, the design assumes that treatment effects will be tier-specific and not spread to untreated tiers. Routledge/Taylor & Francis Group. 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. Multiple baseline designs can rigorously control 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 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. A multiple baseline design with tiers conducted at different times during each day could show disruption due to this coincidental event in the tier assessed early in the day but not in tiers that are assessed later in the day. Book (2011). However, current practice provides little or no direct information on either the temporal duration (e.g., number of days) of baseline nor the offset between phase changes in real time (i.e., number of calendar days between phase changes). Behavior Research Methods, 43(4), 971980. Perhaps a more general and powerful triad of processes that support demonstration of experimental control would be prediction, contradiction, and replication. Two articles published in 1981 described and advocated the use of nonconcurrent multiple baseline designs (Hayes, 1981; Watson & Workman, 1981). AB Design. Three children (ages 4;3 to 5;3) with moderate-severe to severe SSDs participated in two cycles of therapy. Cooper, J. O., Heron, T. E., & Heward, W. L. (2020). 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. 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). WebThe main disadvantage of the multiple baseline design is that a high degree of planning is required to produce a successful implementation. 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. in their classic 1968 article that defined applied behavior analysis. 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. 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. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. This would draw attention to the relationship between the prediction from baseline and the (possible) contradiction of that prediction by the obtained treatment-phase data, and the replication of this prediction-contradiction pair in subsequent 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. The concurrent multiple baseline design opened up many new opportunities to conduct applied research in contexts that were not amenable to other SCDs. 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. Or in a multiple baseline across settings that are assessed at different times of the day, a socially challenging event such as an increase in daily bullying on a morning bus ride could disrupt the target behavior of a participant for the first hour of the day, but have reduced effects thereafter. For example, instrumentation is addressed primarily through observer training, calibration, and IOA. 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. . 2023 Springer Nature Switzerland AG. (p. 325), Compared to its concurrent multiple baseline design sibling, a non-concurrent arrangement is inherently weaker . A given period of maturation may affect various participants, various behaviors, or behaviors in various settings in different ways. WebWeaknesses of multiple baseline designs: There are certain functional relations that may not be clearly understood by this design This design is time consuming and 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 In this design, behavior is measured across either multiple individuals, behaviors, or settings. 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. 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). Department of Educational Psychology, Neag School of Education, University of Connecticut, Storrs, CT, 06269, USA, You can also search for this author in 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 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. (Similar arguments can be made for comparisons across settings, persons, and other variables that might define tiers.) 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. Multiple baseline procedure. Google Scholar. Kazdin, A. E., & Kopel, S. A. We can strongly argue that all tiers contact testing and session experience during baseline because we schedule and conduct these sessions. Multiple baseline and multiple probe designs. Consequently, it is often difficult or impossible to dismiss rival hypotheses or explanations. must have stable baseline and tx in first bx 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. 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. 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. Poor execution can certainly worsen these problems, but good execution cannot eliminate them. Perspectives on Behavior Science, 43, 605616. WebA multiple baseline design across behaviors was used to examine intervention effects. 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 . 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. Strategies and tactics of behavioral research. 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. Third, patterns of results influence the number of tiers needed to yield definitive conclusions. This paper describes procedures for using these designs, https://doi.org/10.1016/0005-7916(81)90055-0, Wolfe, K., Seaman, M. A., & Drasgow, E. (2016). We challenge this assertion. 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. This critical requirement is mainly addressed by the lag between phase changes in successive phases. However, we can never ensure that any two contexts or any two session times are not subject to unique events during the study. Single case experimental design and empirical clinical practice. 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. Perspectives on Behavior Science In this article, we argue that the primary reliance on across-tier comparisons and the resulting deprecation of nonconcurrent designs are not well-justified. Although publication dates would suggest that Kazdin and Kopel (1975) was published before Hersen and Barlow (1976), Kazdin and Kopel cite Hersen and Barlow, and not the other way around. https://doi.org/10.1007/s40614-022-00343-0, SI: Commentary on Slocum et al, Threats to Internal Validity. 288335). This insensitivity is not due to poor experimental design or implementation, it is built in to the nature of multiple baseline designs across participants. Thus, both of the articles introducing nonconcurrent multiple baselines made explicit arguments that replicated within-tier comparisons are sufficient to address the threat of coincidental events. https://doi.org/10.1007/s40614-022-00343-0, DOI: https://doi.org/10.1007/s40614-022-00343-0. Threats to Internal Validity in Multiple-Baseline Design Variations, https://doi.org/10.1007/s40614-022-00326-1, Concurrence on Nonconcurrence in Multiple-Baseline Designs: A Commentary on Slocum et al. 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. 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). Reasons for these specifications will become clear later in the article.) 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. https://doi.org/10.1002/bin.191, Article 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. Journal of Applied Behavior Analysis, 1(1), 9197. The details of situations in which this across-tier comparison is valid for ruling out threats to internal validity are more complex than they may appear. PubMed Central https://doi.org/10.1901/jaba.1968.1-91, Article However, it does not rule out maturation as an alternative explanation of the change in behavior. Natural multiple baselines across persons: A reply to Harris and Jenson. Although the across-tier comparison may detect some coincidental events; it cannot be assumed to detect them all. Still, for a given study, the results influence the number to tiers required in a rigorous multiple baseline design. 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. If A changes after B is put into practice, a researcher can draw the Conclusion that B caused A to change. 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. Carr, J. E. (2005). 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. Hayes, S. C. (1981). The across-tier comparison of concurrent multiple baseline designs is less certain and definitive than it may appear. Interrater agreement on the visual analysis of individual tiers and functional relations in multiple baseline designs. - 181.212.136.34. For both types of comparisons, addressing maturation begins with an AB contrast in a single tier. 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. 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. 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. Behavioral Interventions, 20(3), 219224. https://doi.org/10.1177/0145445516644699, Department of Special Education & Rehabilitation Counseling, Utah State University, 2865 Old Main Hill, Logan, UT, 84322, USA, Timothy A. Slocum,Sarah E. Pinkelman,P. Raymond Joslyn&Beverly Nichols, You can also search for this author in This has been the sharpest point of criticism of nonconcurrent multiple baselines. (Our specification of phase change offset in terms of real time, days in baseline, and sessions in baseline is unusual. (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. 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. Routledge/Taylor & Francis Group. The assumption that all tiers respond similarly to maturation may be somewhat more problematic. 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. Slider with three articles shown per slide. WebThe first quality of ideal baseline data is stability, meaning that they display limited variability. Under the proposed definition, such a study would not be considered a full-fledged multiple baseline. https://doi.org/10.1177/0741932512452794, Lanovaz, M. J., & Turgeon, S. (2020). Data analysis issues concern two closely related questions: (1) Was there a change in data patterns after the phase change? Hersen, M., & Barlow, D. H. (1976). 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. And researchers generally design and implement interventions, select tiers, and employ measures that will likely show consistent treatment effects. Control for testing and session experience requires attention to the number of sessions that participants experience. Single-case research designs: Methods for clinical and applied settings (3rd ed.). Single-case experimental designs: A systematic review of published research and current standards. 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. 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. 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. Estimating reliabilities and correcting for sampling error in indices of within-person dynamics derived from intensive longitudinal data, Optimizing Detection of True Within-Person Effects for Intensive Measurement Designs: A Comparison of Multilevel SEM and Unit-Weighted Scale Scores, https://doi.org/10.1023/B:JOBE.0000044735.51022.5d, https://doi.org/10.1037/0022-006X.49.2.193, https://doi.org/10.1177/001440290507100203, https://doi.org/10.1016/S0005-7894(75)80181-X, https://doi.org/10.1007/s40614-020-00263-x, https://doi.org/10.3758/s13428-011-0111-y, https://doi.org/10.1016/0005-7916(81)90055-0, http://creativecommons.org/licenses/by/4.0/, SI: Commentary on Slocum et al, Threats to Internal Validity. 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. Hayes, S. C. (1985). 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. 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. However, if this within-tier pattern is replicated in multiple tiers after differing numbers of baseline sessions, this threat becomes increasingly implausible. WebAnother limitation cited for single-subject designs is related to testing. The multiple baseline design was initially described by Baer et al. 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. They do not elaborate on the importance of this type of comparison. 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. The general steps for the development of the line graphs are as follows: 1. Sidman, M. (1960). Baer, D. M., Wolf, M. M., & Risley, T. R. (1968). Psychological Methods, 17(4), 510550. 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]. Thus, a multiple baseline with phase changes sufficiently lagged (in terms of number of sessions) provides rigorous control for this threat. ), Single case research methodology: Applications in special education and behavioral sciences (pp. Behavior Modification, 40(6), 852873. An example of multiple baseline across behaviors might be to use feedback to develop a comprehensive exercise program that involves stretching, aerobic exercise, Pearson. 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). Part of Springer Nature. PubMedGoogle Scholar. The use of single-subject research to identify evidence-based practice in special education. What are the benefits and problems of these designs? One area that has, in the past, been particularly controversial is the experimental rigor of concurrent versus nonconcurrent multiple baseline designs; that is, the degree to which each can rule out threats to internal validity. Kazdin, A. E. (2021). It is surprising that there is no single consensus definition of multiple baseline designs. (1968) who emphasized the replicated within-tier comparison. Therefore, we believe that these features should be explicitly included in the definition of multiple baseline designs. The current SCD methodological literature and most SCD textbooks claim that because the tiers of nonconcurrent multiple baseline are not synchronized in real time they have a diminished capacity to control for extraneous variables, in particular coincidental events (e.g., Carr, 2005; Gast et al., 2018; Harvey et al., 2004; Johnston et al., 2020).

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