Multimodal assessments of therapist characteristics are largely unrelated to patient outcomes: A preregistered analysis.

While it is known that therapists vary in effectiveness, it is unclear what therapist-level characteristics predict this variation. We conducted a large-scale, preregistered study (n = 97 therapists from the United States and Canada, n = 6,152 patients) examining a multimodal set of 38 therapist-level predictors that have been empirically or theoretically linked with patient outcomes. We examined associations with pre-post change and rate of change in psychological distress, and likelihood of attending >1 treatment session. We largely did not find associations between therapist-level characteristics and patient outcomes. Most predictors failed to replicate across sensitivity analyses and/or were non-significant following p-value correction. The most robust evidence suggested that interpersonal capacities assessed via a performance task are associated with likelihood of attending >1 treatment session. A key limitation of the study is small therapist effects which may have reduced statistical power. Empirically, it remains uncertain what qualities characterize highly effective therapists.