This research sought to uncover the extent to which Foulds Personal Illness Model would be able to organize psychiatric diagnostic data in a meaningful way. At the same time it was tried to replicate earlier research findings in a Dutch psychiatric cohort study, using identical diagnostic data and analysis techniques.

It was found that Foulds model was applicable in 83.5 per cent of the diagnostic data; that the chosen operationalisations of the model turned out to be uni-dimensional, and to have robust psychometric qualities in terms of scalability and reliability.

In using the same diagnostic material and analysis techniques, it was possible to replicate earlier findings in a Dutch cohort study.