Real world occupational epidemiology, part 2: a visual interpretation of statistical significance

Tests of significance in contingency tables represent one of the most useful techniques in occupational epidemiology, and one from which odds ratios (ORs) can be derived to illustrate the probability that an event occurs compared to the probability that it does not. ORs have become a regularly used tool for estimating the relationship between 2 variables, as well as offering a convenient interpretation of case-control studies. ORs are often used to signify another fundamental concept in Environmental and Occupational Health (EOH), that being the relative risk (RR) of contracting a particular disease following exposure to a particular hazard. RR estimated by the OR have become a de facto standard for representing “hazard” in modern EOH, partly out of tradition, and partly because the OR can provide a reasonable approximation of the RR given certain conditions.