Google Scholar. Features of the target behaviors, participants, measurement, and so forth can make threats to internal validity more or less likely. Tactics of scientific research. 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. 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. 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. 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. 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. It would be an even greater concern if the treatment were an instructional program that requires several weeks or months to implement. And researchers generally design and implement interventions, select tiers, and employ measures that will likely show consistent treatment effects. Cooper et al. 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. 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. Book Hayes, S. C. (1985). 288335). Additionally, the This is a preview of subscription content, access via your institution. To summarize, the replicated within-tier analysis with sufficient lag can rigorously control for the threat of maturation. Single case experimental design and empirical clinical practice. 7. Finally, we make recommendations for more rigorous use, reporting, and evaluation of multiple baseline designs. et al. https://doi.org/10.4324/9781315537085. (1968) who emphasized the replicated within-tier comparison. 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. Although many maturational changes are gradual, more sudden changes are possible. Psychological Methods, 17(4), 510550. 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. Wacker, D., Berg, W., Harding, J., & Cooper-Brown, L. (2004). . This controversy began soon after the first formal description of nonconcurrent multiple baseline designs by Hayes (1981) and Watson and Workman (1981). Single-case research designs: Methods for clinical and applied settings (3rd ed.). Three phonological patterns were targeted for each child. https://doi.org/10.1177/001440290507100203, Johnston, J. M., Pennypacker, H. S., & Green, G. (2020). Strategies and tactics of behavioral research and practice (4th ed.). In this design, behavior is measured across either multiple individuals, behaviors, or settings. PubMedGoogle Scholar. Craig H. Kennedy. Controlling for coincidental events requires attention to the specific dates on which events occur. 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. Watson and Workman (1981) noted that the requirement that observations be taken concurrently clearly poses problems for researchers in applied settings (e.g., schools, mental health centers), since clients with the same target behavior may only infrequently be referred at the same point in time (p. 257). 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. For example, in a study of language skills in typically developing 3-year-old children, maturation would be a particular concern. We examine how these comparisons address maturation, testing and session experience, and coincidental events. 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. - 181.212.136.34. 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. 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. If each tier of a multiple baseline represents a different participant in a different environment (e.g., school versus clinic) located in a different city, this would further reduce the chance that any single event or pattern of events could have contacted the participants coincident with the phase changes. 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. Part of Springer Nature. The within-tier analysis seeks replication of these potential treatment effects in additional tiers of the design. Recommendations for reporting multiple-baseline designs across participants. Create the graph from the data in Sheets; 3. The author has no known conflicts of interest to disclose. 234235). Any alternative explanation of this pattern of results would have to posit an alternative set of causes that could plausibly result in changes in the dependent variable in this specific pattern across the multiple tiers. 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 However, ina concurrent multiple baseline across settings a setting-level event would contact only a single tierthe design would be inherently insensitive to these coincidental events. This pattern seriously weakens the argument that the independent variable was responsible for the change in the treated tier. https://doi.org/10.1037/a0029312, Watson, P. J., & Workman, E. A. Rather, the passage of time allows for more opportunities for participants to interact with their environmentleading to maturational changes. 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. 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). The lag between phase changes must be long enough that maturation over any single amount of time cannot explain the results in multiple tiers. The use of continuous assessment and multiple experimental phases in single-subject research designs allow for detailed examinations of In general, a longer lag is better because it reduces the chance that an event could impact multiple tiers. When conditions are less ideal, additional tiers may be necessary. What are the benefits and problems of these designs? 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. 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. 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 The multiple baseline design is useful for interventions that are irreversible due to learning effects, and when treatment cant be withdrawn. Webtreatment (Kazdin & Nock, 2003). (1973). Google Scholar. Behavioral Interventions, 20(3), 219224. Learn more about Institutional subscriptions. Thus, a multiple baseline with phase changes sufficiently lagged (in terms of number of sessions) provides rigorous control for this threat. Create the data table in Sheets; 2. 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 . Type I Errors and Power in Multiple Baseline Designs, Assessing consistency of effects when applying multilevel models to single-case data. Application of multiple baseline designs in behavior analytic research: Evidence for the influence of new guidelines. 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. https://doi.org/10.4324/9781315150666, Chapter Journal of Behavioral Education, 13(4), 213226. Coincidental events include divorce, changing of living situation, changes in school or work schedule, physical injury, changes in a setting such as construction, changes in coworkers or staffing, and many others. PubMed 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. 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. 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. (p. 365), Of course, the major problem with this [nonconcurrent multiple baseline] strategy is that the control for history (i.e., the ability to assess subjects concurrently) is greatly diminished. Perspectives on Behavior Science, 43, 605616.
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