Pragmatic versus explanatory trials.

This article considers the distinction between "explanatory" and "pragmatic" aims in clinical trials--the distinction between testing a biological hypothesis and providing evidence to permit a choice between alternative treatment policies. The choice of treatments to compare, the selection of patients for the trial, the study size, and how the treatment comparison should be made are among the matters discussed. In general, where explanatory and pragmatic aims conflict, the pragmatic aim will often take priority.