Pragmatic and explanatory trials in the evaluation of the experimental National Health Service nursing homes.

This paper reviews the issues which arose in the design of a randomized controlled trial of three experimental National Health Service nursing homes. Problems associated with the implementation of the trial included ethical issues, choice of sample size and recruitment of subjects to the trial, choice and validity of measures of outcome, evaluation of outcomes and replicability of findings. The distinction between explanatory and pragmatic trials is shown to overcome some of these problems. [ABSTRACT FROM AUTHOR]