An Improved Two Independent-Samples Randomization Test for Single-Case AB-Type Intervention Designs: A 20-Year Journey

Abstract

Detailed is a 20-year arduous journey to develop a statistically viable two-phase (AB) single-case two independent-samples randomization test procedure. The test is designed to compare the effectiveness of two different interventions that are randomly assigned to cases. In contrast to the unsatisfactory simulation results produced by an earlier proposed randomization test, the present test consistently exhibited acceptable Type I error control under various design and effect-type configurations, while at the same time possessing adequate power to detect moderately sized intervention-difference effects. Selected issues, applications, and a multiple-baseline extension of the two-sample test are discussed.

The randomized marker method for single-case randomization tests: Handling data missing at random and data missing not at random

“…Ensuring at least three measurements per phase, this also meets the minimum standards set by . We implemented the restricted Marascuilo-Busk randomization procedure for MBD, as recommended by Levin et al (2019).…”

Randomized Single-Case Intervention Designs and Analyses for Health Sciences Researchers: A Versatile Clinical Trials Companion

“…With that process, at least 3 of the outcome observations will be associated with each participant's A phase and at least 3 of them will be associated with each participant's B or C phase. When, in addition, the participants are randomly assigned to those tier positions, viable statistical randomization test possibilities become available [26][27][28]. Convincing evidence of an intervention effect is present when expected changes in each participant's outcome measure is coincident with the point of, or just following, the introduction of the intervention (i.e., at each participant's staggered intervention start-point position).…”