Question 3: How can we interpret the odds ratio 0.94 in this study?
This is case control study and glioma is a rare condition, so we can interpret the odds ratio as an estimate of the relative risk. We estimate that the risk of glioma for mobile phone users is 0.94 times the risk among non-mobile-phome-users.
This is because the odds ratio is unaffected by the ratio of cases to controls and so the odds ratio from the case-control study is an estimate of the odds ratio for the entire population. Provided the proportion of cases in the whole population is small, the odds ratio and the relative risk will be vey similar.
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Last updated: 31 Jul, 2006.