A study is looking at breast cancer of women compared cases with non-cases, and found that 75/100 cases used calcium supplements compared with 25/100 of the non-cases. Calculate Cross product ratio
Odds ratio = ad/bc Breast cancer cases Non-cases Used Ca supplements 75 (a) 25 (b) Did not use Ca supplements 25 (c) 75 (d) 100 100 Odds ratio = ad/bc = 75*75/25*25 = 9
9
6
3
12
Case Control Study, Combined Designs