To understand what given scores of the Brief Psychiatric Rating Scale (BPRS) and the Positive and Negative Syndrome Scale (PANSS) mean from a clinical point of view is important for the translation of research results into practice. We therefore (a) compared the absolute change of the BPRS/PANSS with the Clinical Global Impressions Ratings (CGI) -improvement score and the change of the CGI severity score, (b) analyzed whether the severity of illness at baseline had an impact on the latter association, and (c) attempted to replicate previous BPRS findings using a completely different data set based upon the PANSS-derived BPRS. The method used was equipercentile linking of BPRS and CGI ratings from 14 drug trials in acutely ill patients with schizophrenia (n=5970). An absolute reduction of the BPRS/PANSS by approximately 10/15 points corresponded to a CGI change of 'minimally improved' and to a change of the CGI severity score by one severity step. However, the latter associations depended on the severity of symptoms at baseline. Less severely ill patients required less BPRS/PANSS total score reduction to achieve the same CGI-improvement score than more severely ill patients. This effect of initial severity was attenuated using percentage rather than absolute BPRS/PANSS reduction scores. The linking analysis between the absolute BPRS/PANSS reduction and the CGI may have an implication for the interpretation of efficacy differences found in clinical trials, and for sample size estimations. Clinicians seem to base CGI ratings on relative change rather than on absolute change of symptoms.