structural:expansion
Efficacy

There is considerable controversy about whether, or when, psychotherapy efficacy is best evaluated by randomized controlled trials or more individualized idiographic methods.

One issue with trials is what to use as a placebo treatment group or non-treatment control group. Often, this group includes patients on a waiting list, or those receiving some kind of regular non-specific contact or support. Researchers must consider how best to match the use of inert tablets or sham treatments in placebo-controlled studies in pharmaceutical trials. Several interpretations and differing assumptions and language remain. Another issue is the attempt to standardize and manualize therapies and link them to specific symptoms of diagnostic categories, making them more amenable to research. Some report that this may reduce efficacy or gloss over individual needs. Fonagy and Roth's opinion is that the benefits of the evidence-based approach outweighs the difficulties.

There are several formal frameworks for evaluating whether a psychotherapist is a good fit for a patient. One example is the Scarsdale Psychotherapy Self-Evaluation (SPSE). However, some scales, such as the SPS, elicit information specific to certain schools of psychotherapy alone (e.g. the superego).

Many psychotherapists believe that the nuances of psychotherapy cannot be captured by questionnaire-style observation, and prefer to rely on their own clinical experiences and conceptual arguments to support the type of treatment they practice. Psychodynamic therapists increasingly believe that evidence-based approaches are appropriate to their methods and assumptions, and have increasingly accepted the challenge to implement evidence-based approaches in their methods.

A pioneer in investigating the results of different psychological therapies was psychologist Hans Eysenck, who argued that psychotherapy does not produce any improvement in patients. He held that behavior therapy is the only effective one. However, it was revealed that Eysenck (who died in 1997) falsified data in his studies about this subject, fabricating data that would indicate that behavioral therapy enables achievements that are impossible to believe. Fourteen of his papers were retracted by journals in 2020, and journals issued 64 statements of concern about publications by him. Rod Buchanan, a biographer of Eysenck, has argued that 87 publications by Eysenck should be retracted.

The response rate of psychotherapy varies, no reliable changes due to psychotherapy can be found in up to 33% of patients.