ABSTRACT
BACKGROUND: In psychologic and psychiatric research, methodological standards are used to develop an evidence-base for clinical practice. Each method forms ‘evidence’ based on specific methodological assumptions. The choice for a method defines what counts as ‘evidence; thus shaping the organization of clinical practice. METHOD: In this paper, we discuss qualitative analyses of three patient-participants in ‘gold standard’ psychotherapy research, who stood out in the sample for their explicit engagement with the questionnaires. RESULTS: These ‘rich cases’ illustrate how to methodological assumptions can lead to loss of valuable clinical information, which jeopardizes the representativeness and utility of the evidence-base. CONCLUSION: By excluding people from analyzes in advance or during the study, or by losing them ‘in the mean’, we lose the opportunity to offer those people an empirically supported treatment. Therefore, if we want to work evidence-based, we also have to collect evidence for the non-evident.