Concurrence on Nonconcurrence in Multiple-Baseline Designs: A Commentary on Slocum et al. (2022).

Slocum et al. (this issue) provide well-reasoned arguments for the use of nonconcurrent multiple baseline designs in behavior analytic work, despite historical preference for concurrent designs (i.e., simultaneous baseline initiation) and contemporary guidelines in related fields suggesting that nonconcurrent designs are insufficient for evaluating functional relations (What Works Clearinghouse, 2020). I provide a commentary, highlighting major contributions of this article and suggesting areas of further consideration. In sum, I agree with authors that researchers should avoid wholesale dismissal of nonconcurrent designs. I also agree that understanding how multiple-baseline designs control for and allow for detection of threats to internal validity is critical so that authors can apply the variation of the design that allows them to draw confident conclusions about relations between independent and dependent variables.