Are there any good papers that quantify the difference in outcomes across psychotherapy providers?

[Psychferlyfe3000]

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I think I remember seeing a paper that described there being a 10x difference in outcomes between psychotherapists. I am wondering if anyone can point to a paper that quantifies this. Thank you!

 

[clozareal]

Much of this can be found in The Great Psychotherapy Debate: The Evidence for What Makes Psychotherapy Work by Wampold, Bruce E., Imel, Zac E. on Chapter 6.