Single case experimental designs: Strategies for studying behavior change (3rd ed.). However, we can never ensure that any two contexts or any two session times are not subject to unique events during the study. 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. WebAnother limitation cited for single-subject designs is related to testing. 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. Perspectives on Behavior Science, 43, 605616. (pp. 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. An example of multiple baseline across behaviors might be to use feedback to develop a comprehensive exercise program that involves stretching, aerobic exercise, WebThe first quality of ideal baseline data is stability, meaning that they display limited variability. In the case of multiple baseline designs, a stable baseline supports a strong prediction that the data path would continue on the same trajectory in the absence of an effective treatment; these predictions are said to be verified by observing no change in trajectories of data in other tiers that are not subjected to treatment; and replication is demonstrated when a treatment effect is seen in multiple tiers. Book Multiple baseline and changing criterion design Flashcards One is that if a If, in the initial tier, a pattern of stable baseline data is followed by a distinct change soon after the phase change, this constitutes a potential treatment effect. The assumption that all tiers respond similarly to maturation may be somewhat more problematic. For example, in a study of language skills in typically developing 3-year-old children, maturation would be a particular concern. National Center for Biotechnology Information WebOften creates lots of problems BAB Reversal Design Doesnt enable assessment of effects prior to the intervention May get sequence effects May be appropriate with dangerous behaviors Addresses ethics of withholding effective treatment Need to be careful when using NCR Reversal Technique Noncontingent reversal Neither the within-tier comparison, nor the across-tier comparison depends on the tiers being conducted simultaneously; both types of comparisons only require that phase changes occur after substantially different amounts of time since the beginning of baselinethat is, each tier is exposed to different amounts of maturation (i.e., days) prior to the phase change. Correspondence to Although the across-tier comparison may detect some coincidental events; it cannot be assumed to detect them all. https://doi.org/10.1016/0005-7916(81)90055-0, Wolfe, K., Seaman, M. A., & Drasgow, E. (2016). The multiple baseline design was initially described by Baer et al. Therefore, we believe that these features should be explicitly included in the definition of multiple baseline designs. Two articles published in 1981 described and advocated the use of nonconcurrent multiple baseline designs (Hayes, 1981; Watson & Workman, 1981). Multiple We are not pointing to flaws in execution of the design; we are pointing to inherent weaknesses. PubMed 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. Kennedy, C.H. The use of single-subject research to identify evidence-based practice in special education. Rand McNally. 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. Textbooks commonly describe and characterize the design without clearly defining it. In this article, we first define multiple baseline designs, describe common threats to internal validity, and delineate the two bases for controlling these threats. However, researchers in clinical, educational, and other applied settings recognized that they could expand research much further if the tiers of a multiple baseline could be conducted as they became available sequentially rather than simultaneously. 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. The issue of concurrence of tiers should be considered along with many other design variations that can be manipulated to create a design that fits the particular experimental challenges of a particular study. https://doi.org/10.1002/bin.191, Article In a concurrent multiple baseline that involves a single participant across settings, behaviors, antecedent stimuli etc., this kind of event would be expected to contact all tiers. Kazdin, A. E. (2021). 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 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. Taplin, P. S., & Reid, J. This information would allow readers to evaluate the sufficiency of each dimension of lag given the specific characteristics of the particular study. These variables share the key characteristic that their impact would be expected to accumulate as a function of number of experimental sessions. 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. The purposes of this article are to (1) thoroughly examine the impact that threats to internal validity can have on concurrent and nonconcurrent multiple baseline designs; (2) describe the critical features of each design type that control for threats to internal validity; and (3) offer recommendations for use and reporting of concurrent and nonconcurrent multiple baseline designs. Campbell, D. T., & Stanley, J. C. (1963). Addressing the second question requires data analysis that is informed by the specifics of the study. The across-tier comparison of concurrent multiple baseline designs is less certain and definitive than it may appear. Pearson Education. Using Single-Case Designs in Practical Settings: Is Within-Subject Replication Always Necessary? Coincidental events share the characteristic that their behavioral impact is expected to be a function of particular dates. must have stable baseline and tx in first bx 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. Google Scholar, Gast, D. L., Lloyd, B. P., & Ledford, J. R. (2018). 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. 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. Horner, R. H., Carr, E. G., Halle, J., McGee, G., Odom, S., & Wolery, M. (2005). Throughout this article we have argued that controlling for the three main threats to internal validitymaturation, testing and session experience, and coincidental eventsin multiple baseline designs requires attention to three distinct dimensions of lag of phase changes across tiers. Behavioral Interventions, 33(2), 160172. 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. PubMedGoogle Scholar. With stable data, the range within which future data points will fall is The withdrawal phase of an A-B-A design is important because it shows that the results of the intervention weren't just a result of a difference in time. Without the latter you cannot conclude, with confidence, that the intervention alone is responsible for observed behavior changes since baseline (or probe) data are not concurrently collected on all tiers from the start of the investigation. Coincidental events might be expected to be more variable in their effect than interventions that are designed to have consistent effects. 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). To summarize, the replicated within-tier analysis with sufficient lag can rigorously control for the threat of maturation. Pearson Education. Ten sessions of baseline would be expected to have similar effects whether they occur in January or June. In the past, there was significant controversy regarding the relative rigor of concurrent and nonconcurrent multiple baseline designs. Research methodologists have identified numerous potential alternative explanations that are threats to internal validity (e.g., Campbell & Stanley, 1963; Cooper et al., 2020; Kazdin, 2021; Shadish et al., 2002). The reversal model is fine for many questions, but in some instances, removing a type of treatment could be unwise or even unethical. Single-case research designs: Methods for clinical and applied settings (3rd ed.). 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. Routledge. Features of the target behaviors, participants, measurement, and so forth can make threats to internal validity more or less likely. 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. 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. 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. These could include presence of observers, testing procedures, exposure to testing stimuli, attention from implementers, being removed from the typical setting, exposure to a special setting, and so on. Department of Educational Psychology, Neag School of Education, University of Connecticut, Storrs, CT, 06269, USA, You can also search for this author in In the end, judgments about the plausibility of threats and number of tiers needed must be made by researchers, editors, and critical readers of research. 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. 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. Given that multiple baseline designs make up such a large proportion of the existing SCD literature and current research activity, it is critical that SCD researchers thoroughly understand the specific ways that multiple baseline designs address potential threats to internal validity so that they can make experimental design decisions that optimize internal validity and accurately evaluate, discuss, and interpret the results of their research. Routledge/Taylor & Francis Group. 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. Part of Springer Nature. Experimental and quasi-experimental designs for generalized causal inference. What are the benefits and problems of these designs? 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 (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. As Kazdin and Kopel (1975) pointed out, multiple baseline designs require that the effects of the independent variable must have tier-specific effects, yet the across-tier analysis requires that extraneous variables must not have tier-specific effects. https://doi.org/10.1007/s40614-022-00326-1, DOI: https://doi.org/10.1007/s40614-022-00326-1. Independent from Watson and Workman (1981), Hayes (1981) published a lengthy article introducing SCDs to clinical psychologists and made the point that these designs are well-suited to conducting research in clinical practice. 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. 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. To answer the first question, the one must distinguish signal (systematic change) from noise (unsystematic variance). Throughout their discussion of SCD, these authors describe experimental control in terms of three processes: prediction, verification, and replication. 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). Johnston, J. M., Pennypacker, H. S., & Green, G. (2010). The multiple baseline family of designs includes multiple baseline and multiple probe designs. In this design, behavior is measured across either multiple individuals, behaviors, or settings. Webtreatment (Kazdin & Nock, 2003). They do not mention the across-tier comparison, presumably because they believe that this analysis is not necessary to establish experimental control. Single-case intervention research design standards. 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. All three of these dimensions of lag are necessary to rigorously control for commonly recognized 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. Nonconcurrent multiple baseline designs, however, do not afford this comparison. Each replication requires an assumption of a separate event coinciding with a distinct 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). These baseline-treatment comparisons, which we will refer to as tiers, differ from one another with respect to participants, behaviors, settings, stimulus materials, and/or other variables. This controversy began soon after the first formal description of nonconcurrent multiple baseline designs by Hayes (1981) and Watson and Workman (1981). Third, patterns of results influence the number of tiers needed to yield definitive conclusions. Create the graph from the data in Sheets; 3. This insensitivity is not due to poor experimental design or implementation, it is built in to the nature of multiple baseline designs across participants. 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). However, an across-tier comparison is not definitive because testing or session experience could affect the tiers differently. - 181.212.136.34. Further, if the potential treatment effect is more gradual (as one might expect from an educational intervention on a complex skill), maturational changes may be impossible to distinguish from treatment effects. Multiple Baseline Flashcards | Quizlet For example, it is implausible that the effects of maturation would coincide with a phase change after 5 days in one tier, after 10 days in a second tier, and after 15 days in a third. Behavior Research Methods, 43(4), 971980. The concurrent multiple baseline design opened up many new opportunities to conduct applied research in contexts that were not amenable to other SCDs. Both concurrent and nonconcurrent multiple baseline designs also afford the same across-tier comparison; both can show a potentialtreatment effect after a certain number of baseline sessions in one tier and a lack of effect after that same number of sessions in another tier. 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. The authors discuss two designs commonly used to demonstrate reliable control of an important behavior change (p. 94). 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. 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. Concurrent and nonconcurrent multiple baseline designs address maturation in virtually identical ways through both within- and across-tier comparisons. Controlling for coincidental events requires attention to the specific dates on which events occur. Google Scholar. Perspect Behav Sci 45, 619638 (2022). Concurrent multiple baseline designs are multiple baseline designs in which the tiers are synchronized in real time. Slider with three articles shown per slide. 288335). Likewise, setting-level coincidental events are those that contact a single setting. The Nonconcurrent Multiple-Baseline Design: It is What it Perspectives on Behavior Science Behavioral cusps: A developmental and pragmatic concept for behavior analysis. 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. This pattern seriously weakens the argument that the independent variable was responsible for the change in the treated tier. WebDisadvantage: Covariance among subjects may emerge if individuals learn vicariously through the experiences of other subjects Also, identifying multiple subjects in the same 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). Finally, practitioners whose work may be influenced by SCD research must understand these issues so they can give appropriate weight to research findings. 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. PubMed Central Journal of Consulting & Clinical Psychology, 49(2), 193211. (1981). 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. For example, Gast et al. 2023 Springer Nature Switzerland AG. 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. 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 . . 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. That is, session numbers do not necessarily correspond to the same periods of real time across tiers. Effects of instructional set and experimenter influence on observer reliability. Cooper et al. In J. R. Ledford & D. L. Gast (Eds. A COMPARISON OF MULTIPLE BASELINE FAMILY OF PubMedGoogle Scholar. Multiple baseline designs can rigorously control these threats to internal validity. 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. Hersen, M., & Barlow, D. H. (1976). 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. The present article is focused on the second questionwhether systematic changes in data can be attributed to the treatment. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Maturational changes may be smooth and gradual, or they may be sudden and uneven. Hayes, S. C. (1981). Threats to Internal Validity in Multiple-Baseline Design https://doi.org/10.1901/jaba.1968.1-91, Article Houghton Mifflin. The across-tier comparison provides another possible source of control for maturation. Given this dilemma, priority should be given to optimizing the within-tier comparisons because this is the comparison that can confer stronger control.