The reliability of the Personal and Social Performance scale - informing its training and use.

Social functioning is as an important outcome in studies of people with schizophrenia. Most measures of social function include a person's ability to manage everyday activities as well as their abilities to engage in leisure and occupational activities. The Personal Social Performance (PSP) scale assesses functioning across four dimensions (socially useful activities, personal and social relationships, self-care, disturbing and aggressive behaviours) rather than one global score and thus has been reported to be easier to use. In a pan-European study of people with severe mental illness a team of 26 researchers received training in rating the scale, after which the inter-rater reliability (IRR) was assessed and found to be not sufficiently high. A brief survey of the researchers elicited information with which to explore the low IRR and their experience of using the PSP. Clinicians were found to have higher IRR, in particular, psychologists. Patients' employment status was found to be the most important predictor of PSP. Researchers used multiple sources of information when rating the scale. Sufficient training is required to ensure IRR, particularly for non-clinical researchers, if the PSP is to be established as a reliable research tool.