The total scores of the scales, and individual clinical, personality, and bio­graphical items were subjected to Principal Component Analysis. A series of sequential analyses indicated the stability of the clusters derived. Figure 1 illus­trates a typical outcome of this analysis, with symptoms and personality scores included. It can be seen that the upper right-hand quadrant contains a cluster of items that are consistent with the entity depression; similarly in the upper left-hand quadrant is a cluster consistent with the term anxiety. These data were reanalyzed a number of times, leaving out a variety of items on each occasion and were also analyzed separately for sex. No matter which items were included or excluded, the basic patterns established remained invariant.


























It could be said, therefore, that the general factor here is a measure of extensive severity (14), in so far as it is a measure of the total number of symptoms. Toward the right outer limit of the depression clusters is the item rating of global severity. This is the position it occupies in most other Principal Component Analyses. This item could be said to reflect intensive severity (of depression). Figure 2 describes the relationship of all the established scales to the clusters f anxiety and depression. As can be seen, the BDI and ZDS poorly reflect the depression clusters. They may be good extensive measures of mood disturbance, but they have a low correlation with intensive measures of depression. The HAS would not appear to reflect anxiety accurately enough.

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