RT Journal A1 Spitzer RL, Endicott J, Williams JW T1 REsearch diagnostic criteria JF Archives of General Psychiatry JO Archives of General Psychiatry YR 1979 FD November 1 VO 36 IS 12 SP 1381 OP 1382 DO 10.1001/archpsyc.1979.01780120111013 UL http://dx.doi.org/10.1001/archpsyc.1979.01780120111013 AB To the Editor—  Although we welcome discussion of the relative merits of different research criteria for Psy chiatric diagnosis, the article by Drs Overall and Hollister in the Archives (36:1198-1205, 1979) "Comparative Evaluation of Research Diagnostic Criteria for Schizophrenia" troubles us for several reasons. First of all, the authors do not address the issue of the different purposes of various sets of research diagnostic criteria. Whereas the purpose of the actuarial approach taken by Drs Overall and Hollister is to simulate competent or expert clinical practice, the purpose of the Washington University criteria, research diagnostic criteria (RDC), and DSMIII criteria is to improve usual clinical practice by incorporating into the criteria distinctions that have been shown by research study to have some validity in terms of such variables as course, response to specific therapy, familial pattern, etc. Given this difference in purpose, it is hardly adequate to approach the evaluation