Psychometric Properties of "Community Assessment of Psychic Experiences": Review and Meta-analyses

Abstract

The Community Assessment of Psychic Experiences (CAPE) has been used extensively as a measurement for psychosis proneness in clinical and research settings. However, no prior review and meta-analysis have comprehensively examined psychometric properties (reliability and validity) of CAPE scores across different studies. To study CAPE's internal reliability--ie, how well scale items correlate with one another--111 studies were reviewed. Of these, 18 reported unique internal reliability coefficients using data at hand, which were aggregated in a meta-analysis. Furthermore, to confirm the number and nature of factors tapped by CAPE, 17 factor analytic studies were reviewed and subjected to meta-analysis in cases of discrepancy. Results suggested that CAPE scores were psychometrically reliable--ie, scores obtained could be attributed to true score variance. Our review of factor analytic studies supported a 3-factor model for CAPE consisting of "Positive", "Negative", and "Depressive" subscales; and a tripartite structure for the Negative dimension consisting of "Social withdrawal", "Affective flattening", and "Avolition" subdimensions. Meta-analysis of factor analytic studies of the Positive dimension revealed a tridimensional structure consisting of "Bizarre experiences", "Delusional ideations", and "Perceptual anomalies". Information on reliability and validity of CAPE scores is important for ensuring accurate measurement of the psychosis proneness phenotype, which in turn facilitates early detection and intervention for psychotic disorders. Apart from enhancing the understanding of psychometric properties of CAPE scores, our review revealed questionable reporting practices possibly reflecting insufficient understanding regarding the significance of psychometric properties. We recommend increased focus on psychometrics in psychology programmes and clinical journals.

Keywords: psychosis proneness; reliability; reliability generalization; validity.

Fig. 1.

Distribution of original Cronbach’s alpha values of CAPE-42, CAPE-pos, CAPE-neg, and CAPE-dep. The solid and dashed lines represent the group mean and the acceptable level of reliability respectively.

Fig. 2.

Structure of CAPE-42 consisting of CAPE-pos, CAPE-neg, and CAPE-dep with their respective subdomains.