As established in several studies, therapists differ in effectiveness. A vital research task now is to understand what characterizes more or less effective therapists, and investigate whether this differential effectiveness systematically depends on client factors, such as the type of mental health problem. The purpose of the current study was to examine whether therapists are universally effective across patient outcome domains reflecting different areas of mental health functioning. Data were obtained from 2 sites: the Research Consortium of Counseling and Psychological Services in Higher Education (N = 5,828) in the United States and from primary and secondary care units (N = 616) in Sweden. Outcome domains were assessed via the Outcome Questionnaire-45 (Lambert et al., 2004) and the CORE-OM (Evans et al., 2002). Multilevel models with observations nested within patients were used to derive a reliable estimate for each patient's change (which we call a multilevel growth d) based on all reported assessment points. Next, 2 multilevel confirmatory factor analytic models were fit in which these effect sizes (multilevel ds) for the 3 subscales of the OQ-45 (Study 1) and 6 subscales of CORE-OM (Study 2) were indicators of 1 common latent factor at the therapist level. In both data sets, such a model, reflecting a global therapist effectiveness factor, yielded large factor loadings and excellent model fit. Results suggest that therapists effective (or ineffective) within one outcome domain are also effective within another outcome domain. Tentatively, therapist effectiveness can thus be conceived of as a global construct. (PsycINFO Database Record
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