The validity of the assessment of psychopathology in the psychoses.

This paper reviews recent progress in the assessment of the psychopathology of psychosis and focuses upon a number of persistent limitations. In particular the over-emphasis upon reliability at the expense of validity is highlighted and the relationship between reliability and validity is reconsidered. A number of strategies aimed at improving the validity of psychopathological measures are outlined. Proposals to deploy such variables differently in research strategies and analyses are endorsed.