The Delusions-Symptoms-States Inventory (DSSI): construction, applications and structural analyses

This is the third and last report in a series of three articles reviewing and reassessing the late Graham Foulds theoretical conceptions of personality disturbance and personal illness and the scales that were developed to assess them. We have already reported on the Personality Deviance Scales (PDS; Deary et al., 1995) and the Personal Disturbance Scale (DSSI/sAD; Bedford and Deary, 1997). The present report concerns the Delusions-Symptoms-States Inventory (DSSI). The literature on this instrument is reviewed under three broad headings: theoretical background and technical aspects, clinical reviews and other studies. Multivariate analyses of the DSSIs 12 subscales and total structure are reported. All 12 subscales have adequate psychometric characteristics. The higher order structure of the instrument reveals two clear but correlated factors of anxiety and depression-elation. Interpretation of a third higher order factor is less certain. A brief overall assessment of Foulds contribution to differential clinical psychology is made and it is concluded that his theories and clinical psychometric instruments have lasting value