ABSTRACT
Causality, that is to say, understanding how putative causes might be related to specific effects, has always been a primary concern of epidemiology and public health. In public health, as well as other fields such as social policy and criminal justice, there has also been a growth of interest in understanding the impact of interventions. A useful starting point for thinking about 'cause' is to distinguish it from the concept of association. Associations can be described as 'positive' if an increase in one variable is accompanied by an increase in another. Thus, a high level of low-density lipoprotein cholesterol (LDL) has been identified as a risk factor for coronary heart disease (CHD) in that it is associated with an increased risk of developing the disease. Definitions of causation have developed in response to the rise of chronic degenerative diseases as the major causes of mortality and morbidity where, most causes are neither necessary nor sufficient but contributory.
