Confidence intervals for the odds ratio in case-control studies: a calculator program for Cornfield's method.

A Hewlett-Packard 67 calculator program is given to compute confidence intervals for odds ratios in case-control studies, using the method of Cornfield and an algorithm of Fleiss. Recent work by Brown has shown Cornfield's method to be superior to other approximate methods of odds ratio confidence interval computation and to agree closely with Fisher's exact method. Although a calculator program for the exact method is available in the literature, the convergence times are frequently in excess of 30 min. The program for Cornfield's method given below typically yields upper and lower confidence limits in less than 2 min.