Association and causation Studying the incidence of disease in particular groups of people can lead to the discovery of causation what makes it occur For example, the high incidence of lung cancer among cigarette smokers suggests that smoking is a causative factor in the development of lung cancer. However, care must be taken not to assume every association between a disease and a measured variable is causative. To say there is an association between two things simply means that they occur together in a certain situation. For example, several studies have indicated high rates of of their work (perhaps caused by lung cancer in cooks. Although this could be a carcinogens in fumes from frying), it may be simply because professio than the average. In other words, smoking might confound the association with cooking more