Programme evaluation training for health professionals in francophone Africa: process, competence acquisition and use

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The inclusion of ‘then-test’ questions in post-test questionnaires alters post-test responses: a randomized study of bias in health program evaluation

Objectives Program evaluations are frequently based on &lsquo;then-test&rsquo; data, i.e., pre-test collected in retrospect. While the application of the then-test has practical advantages, little is known about the validity of then-test data. Because of the collection of then-test in close proximity to post-test questions, this study was aimed at exploring whether the presence of then-test questions in post-test questionnaires influenced subjects&rsquo; responses to post-test.Patients and methods To test the influence of then-test questions, we designed a randomized three-group study in the context of chronic disease self-management programs. Interventions had comparable goals and philosophies, and all 949 study participants filled out identical Health Education Impact Questionnaires (heiQ) at pre-test. At post-test, participants were then randomized to one of the following three groups: Group A responded to post-test questions only (n = 331); Group B filled out transition questions in addition to post-test (n = 304); and Group C filled out then-test questions in addition to post-test (n = 314).Results Significant post-test differences were found in six of eight heiQ scales, with respondents who filled out then test questions reporting significantly higher post-test scores than respondents of the other groups.Conclusions This study provides evidence that the inclusion of then-test questions alters post-test responses,suggesting that change scores based on then-test data be interpreted with care.<br /