Longitudinal records of anxiety and depression in general practice: the Second National Morbidity Survey

This paper analyses patterns of episodes of anxiety and depression as recorded by 22 general practices which took part in the Second National Morbidity Survey (RCGP, 1980). The data comprise 6 years' records. Simple Markov chains are fitted to each age-group of men and women, and the inter-practice variation in the resulting parameter estimates are compared, using Andrews' plots and principal components plots. The implications for the presentation and interpretation of data from large-scale morbidity surveys are discussed.