ABSTRACT
The term 'ecological association' implies the existence of specific links between the environment and both individuals and groups. In the context of medical geography, the focus is on those relationships which are consequential in disease pathogenesis. May's work emphasised the in-depth analysis of relations between environment and disease; in the Ecology of Human Disease, May provides an eloquent theoretical statement of many of the principles of disease ecology, and then proceeds to apply these concepts to specific diseases. As with most ecological associative analysis, the major task is one of moving from the observation of variation to the statistical, and then the causal, explanation of the variation. Geographical variations in cancer incidence have been studied even more widely than variations in cardiovascular disease. Studies of cancer variation have proliferated in recent years, and much of the sophistication in ecological associative analysis has been derived from cancer studies by geographers and non-geographers alike.
