Conrad has correlated certain personality characteristics (e.g. ability to verbalize feelings) and personality changes during psychotherapy (e.g. becoming less hostile) with the psychotherapist's opinion of the result of psychotherapy on its termination.

Hunt critically discusses several new American research projects on the effects of psychotherapy and proposes an alternative, although more difficult, plan which he considers should be kept before research workers as an ideal.

Eysenck has surveyed nineteen reports on the results of psychotherapy (just over 7, 000 patients) including five reports by psycho-analysts (about 750 patients) and concludes that the statistical uselessness of the reported information 'highlights the necessity of properly planned and executed experimental studies into this important field'.