WHAT DO WE MEAN BY A STATISTICAL-MODEL

Statisticians are too often satisfied by fitting data rather than inve stigating the process out of which the data arose. The assumptions on which they base their models may be quite unrealistic, and while it is true that a model should not be more complicated than necessary, neit her should it be too simple. Ways of approaching several sets of data from different areas of clinical medicine are considered, and differen t attitudes to the purpose of modelling highlighted. The transition fr om smoothing data, through fitting curves, to modelling underlying pro cesses is discussed.