A computer program for calculating ratio estimates.

A computer program is described to calculate ratio estimates for an endpoint measured on patient subunits, such as progression of disease in coronary arteries and extent of dental caries. The program calculates ratio estimates for levels of stratification factors measured in the patient as a unit, e.g. age and sex. Test statistics are computed to evaluate differences in ratio estimates for factors with two levels. A method for making pairwise comparisons for factors with more than two levels is also described, but is not computed by the program. Data from the Veterans Administration Study of Bypass Surgery (Am. J. Cardiol. 40 (1977) 212-225) are used to illustrate the features of the program.