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Table 1 Key differences between trials with explanatory and pragmatic attitudes (from Zwarenstein et al. [48]).

From: Making trials matter: pragmatic and explanatory trials and the problem of applicability


Explanatory attitude

Pragmatic attitude


Efficacy: can the intervention work?

Effectiveness: does the intervention work when used in normal practice?


Well resourced, 'ideal' setting

Normal practice


Highly selected; poorly adherent participants and those with conditions which might dilute the effect are often excluded

Little or no selection beyond the clinical indication of interest


Strictly enforced and adherence is monitored closely

Applied flexibly as it would be in normal practice


Often short-term surrogates, or process measures

Directly relevant to participants, funders, communities and healthcare practitioners

Relevance to practice

Indirect: little effort is made to match the design of the trial to the decision making needs of those in the usual setting in which the intervention will be implemented

Direct: the trial is designed to meet the needs of those making decisions about treatment options in the setting in which the intervention will be implemented