Therapist effects in the National Institute of Mental Health Treatment of Depression Collaborative Research Program and other psychotherapy studies

In summary, our best estimate of therapist differences in outcome from both large-scale multicenter clinical trials like the TDCRP (Elkin et al., 2005), Project MATCH (Project MATCH Research Group, 1998), and the NIDA Cocaine Collaborative Study (Crits-Christoph et al., 1999) is that such effects are typically small; our best estimate from large-scale naturalistic studies (Okiishi et al., 2003) is that such effects are between small and moderate. Nevertheless, research should continue to investigate the conditions under which therapist differences might be apparent in naturalistic settings and routinely conduct preliminary analyses, checking on the presence of therapist effects when analyzing data from efficacy studies. © 2006 Society for Psyhotherapy Research.