A Note on the “One Case per Stagger Position” Character of Common Multiple-Baseline Intervention Designs

ABSTRACT

Purpose: To overcome the constraint of common multiple-baseline designs that only one case per stagger position is permitted.

Methods: Three alternative strategies for assigning more than one case to each stagger position are examined.

Results: The three recommended strategies achieve the objective while maintaining the study’s internal and statistical-conclusion validities.

Conclusions: ExPRT, a freely available Excel-based randomization-test package, can be used to assist in both the design and statistical analysis associated with each of the strategies.

KEYWORDS:

• Multiple-baseline designs
• stagger positions
• single-case intervention research

Acknowledgments

We are grateful to Robert Horner for initially bringing the “more than one case per multiple-baseline stagger position” issue to our attention and to Wendy Machalicek for the valuable input that she provided to this note.