ABSTRACT
Epidemiology is concerned with the study of patterns of disease incidence and prevalence in natural populations, and the identification and estimation of risk factors associated with particular diseases. Traditionally, epidemiological studies only considered spatial risk factors at coarse geographical scales, for example comparing estimates of disease risk in different countries, or otherwise defined administrative regions. The advent of relatively precise post-code systems, together with the inclusion of post-coded information on place of birth, residence or death in disease registers and in census data, made it possible to consider much more detailed patterns of spatial variation in disease risk. For example, the UK post-code system is notionally accurate to an order of magnitude of tens of meters in urban areas, where each post-code typically identifies a single street. As a result, statistical methods have been developed to apply
Spatio-Temporal
the ideas of spatial point processes to epidemiological data, specifically to the study of the observed pattern of disease in relation to possible environmental risk factors. In epidemiology, studies of this kind are often called individuallevel studies. Studies that compare disease rates between different populations are usually called area-level studies or, somewhat quaintly, ecological studies.
