The thesis gives examples of analysing time series data while being employed as statistician at the Industrial and Community Health Research Centre, North Staffordshire Medical Institute, Hartshill Road, Stoke-on-Trent for the period 1988-1997. Topics include:(a) the analysis of asthma data with a view to aid detection and confirmation of occupational asthma. This project highlights possible approaches for modelling regularly and unequally spaced observations (b) modelling bleeding and behavioural patterns of handicapped people using binary valued time series (c) a repeated measures analysis following a surgical intervention (d) a study relating mood scores to progesterone levels