Dawes On What Doesn't Matter In Therapy

First, they discovered that the therapists' credentials - Ph.D., M.D., or no advanced degree - and experience were unrelated to the efficacy of therapy.

Second, they discovered that the type of therapy given was unrelated to its effectiveness, with the possible exception of behavioral techniques, which seemed superior for well-circumscribed behavioral problems.

They also discovered that length of therapy was unrelated to its success.

-Robyn Dawes quoted by Robin Hanson of Overcoming Bias.