Nonconcurrent Multiple-Baseline and Multiple-Probe Designs in Special Education: A Systematic Review of Current Practice and Future Directions

Abstract

Although quality guidelines for single-case intervention research emphasize the importance of concurrent baselines in multiple-baseline and multiple-probe designs, nonconcurrent variations on these designs persist in the research literature. This study describes a systematic review of special education intervention studies ( k = 406) between 1988 and 2020 that report using nonconcurrent multiple-baseline or multiple-probe designs to test interventions for individuals with disabilities ages 21 years and younger. We coded and synthesized study characteristics pertaining to participants, settings, interventions, data reporting, and contextual factors. Findings indicate the prevalence of nonconcurrent designs for intervention studies in a variety of settings addressing social and communication needs of individuals with disabilities. We discuss implications for research and practice and offer suggestions for improving the validity of nonconcurrent designs. A PRISMA-compliant abstract is available at https://osf.io/sdnj5/?view_only=f386b1fe5f14430a8d63fceed293718d .

A review of counseling research using single‐case research design

“…If we include participants that are experiencing similar environments (e.g., same classroom in school), then the baselines of the second and third cases serve as a control when the first case enters intervention (Ledford, 2022). However, others have argued the non‐concurrent (i.e., baseline not collected at the same time) multiple‐baseline design perhaps enhances external validity by demonstrating intervention effectiveness at different time points (Morin et al., 2023). The important takeaway is that either the concurrent or non‐concurrent multiple‐baseline design is providing more credible evidence than an AB design with a single participant or an AB design with multiple participants where the intervention occurs at the same time point for all cases.…”

Teaching argument writing in math class: challenges and solutions to improve the performance of 4th and 5th graders with disabilities

“…A single-case randomized multiple-baseline design (MBD), with random assignment of classrooms to the staggered multiple-baseline levels (“tiers”), was adopted to evaluate the effectiveness of the FACT intervention, because of its high degree of scientific credibility (Kratochwill & Levin, 2010 ; Levin et al, 2018 ). A nonconcurrent version of the design was implemented (Kratochwill et al, 2022 ; Morin et al, 2023 ; Slocum et al, 2022a , 2022b ) because in school settings multiple intermittent unplanned-for events (e.g., irregularities of school-schedule timing, teacher absences, weather conditions, within-school events,) “conspire” to disturb the concurrency of intervention administration. Although the current What Works Clearinghouse’s Single-Case Standards document (WWC, 2022) gives somewhat shorter shrift to nonconcurrent MDs than to concurrent ones, the just-referenced authors suggest that nonconcurrent and concurrent MBDs hold near-equal footing with respect to their internal-validity characteristics.…”

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“…If we include participants that are experiencing similar environments (e.g., same classroom in school) then the baselines of the second, third, etc cases serve as a control when the first case enters intervention (Ledford, 2022). However, others have argued that the nonconcurrent (i.e., baseline not collected at the same time) multiple-baseline design perhaps enhances external validity by demonstrating intervention effectiveness at different time points (Morin et al, 2023). The important takeaway is either the concurrent or nonconcurrent multiple-baseline design is providing more credible evidence than just an AB design.…”