British Journal of Clinical Psychology (2000), 39, 79±94 Printed in Great Britain # 2000 The British Psychological Society 79 A con®rmatory factor analysis of the Hospital Anxiety and Depression scale: Comparing empirically and theoretically derived structures Martin Dunbar*, Graeme Ford, Kate Hunt and Geoå Der Medical Research Council, Medical Sociology Unit, Glasgow, UK Objectives. To compare the ®t of various factor solutions for the Hospital Anxiety and Depression scale (HAD; Zigmond & Snaith, 1983). Design. A cross-sectional postal survey was used to collect the data from community-based participants in the West of Scotland Twenty-07 study. Methods. The HAD scale, a 14-item self-administered measure of anxiety and depression, was completed by 2547 participants from three age cohorts (aged approximately 18, 39 and 58 years). Using con®rmatory factor analyses four models suggested by prior exploratory factor analyses were compared to a model derived from Clark and Watson’s (1991) tripartite theory of anxiety and depression. Results. The model derived from the tripartite theory of anxiety and depression (with factors labelled negative aåectivity, anhedonic depression and autonomic anxiety) produced the closest ®t to the data. This model produced a good ®t in all three cohorts although group comparisons suggested that there were variations in the strength of some factor loadings across the three age groups. A model that had a hierarchical arrangement of the three factors in the tripartite model was also produced. This model ®t the data equally as well as did the `¯at’ tripartite model. Conclusions. Three factors appear to underlie the HAD scale. Research is needed that examines whether or not using sub-scales based on these factors increases the ability of the HAD scale to detect cases of anxiety and depression. There is a wide variety of scales available for the purpose of screening for the presence of psychopathology. The Hospital Anxiety and Depression scale (HAD; Zigmond & Snaith, 1983) is one instrument that is becoming increasingly popular with researchers and practitioners. The HAD scale is a self-administered rating scale that produces two sub-scales, one measuring anxiety and the other measuring depression. It was originally designed for use with physically ill patients in hospital settings although more recently it has been used to screen individuals living in the * Requests for reprints should be addressed to Dr Martin Dunbar, Flat 3}2, 212 Wilton Street, Glasgow G20 6BL, UK.