The following data are from a prospective cohort study in which a sample of people from a town near a toxic waste site was compared to that from a similar town a hundred miles away in the same state.
The outcome was incidence of all types of cancer over a 5 year period.
Town Cancer - yes Cancer - no
A 42 458
B 37 763
What is the odds ratio of cancer in town A compared to town B?
Which is the better measure of association in this study? Why?