Idiographic Clinical Trials: What are they, When are they Useful, and Recent Developments

Ty Ridenour, PhD
RTI International

Stephen Tueller, PhD
RTI International

ABSTRACT:
Within-subject clinical trials have long been considered a lesser option to randomized clinical trials in psychology and medicine and have fallen out of favor for several decades. However, these perceptions of within-subject clinical trials (also referred to as case study experimental designs, quasi-experimental designs, or N-of-1 studies) are largely due to historical limitations or misunderstandings about their purposes and uses. Over the last 10 years, methodological advances and innovative applications of these methods have led to a resurgence in within-subject clinical trials. This presentation will first review the logic and uses of within-subject clinical trials, their traditional methods, and their limitations. With this historical backdrop, recent advances will be presented as well as how these advances elevate the rigor of these studies to merit a new moniker of idiographic clinical trials. Illustrative studies will demonstrate intensive hierarchical regression, unified structural equations modeling, and N=1 analytic approaches.