Consistency checks to improve measurement with the Personal and Social Performance Scale (PSP).

International Society for CNS Clinical Trials and Methodology convened an expert Working Group that assembled consistency/inconsistency flags for the Personal and Social Performance Scale (PSP). One hundred and forty seven flags were identified, 16 flag errors in deriving the PSP decile (i.e., total) score from the four individual domain scores, 74 flag inconsistencies between domain scores relative to Positive and Negative Symptom Scale (PANSS) item ratings and 57 flag inconsistencies between PSP decile score and PANSS items ratings. The flags were applied to assessments from randomized clinical trial data of antipsychotics in schizophrenia from almost 18,000 ratings. Twenty-two flags were raised in at least 5 of 1000 ratings. Nearly 20% of the PSP ratings had at least one inconsistency flag raised. Application of flags to clinical ratings may improve the reliability of ratings and validity of trials.