Key points are not available for this paper at this time.
Quantification of the dependence of the odds ratio on concomitant variables associated with each of several 2 X 2 tables, using a regression model proposed by Zelen 1971, is an important tool for retrospective studies in epidemiology, An "exact" analysis may be based on the conditional likelihood obtained by fixing all the marginal totals. A symptotically this approach is equivalent to use of an unconditional log-linear model. The method is used to reanalyze data reported by Kneale 1971 on the relationship between obstetric radiation and childhood cancer.
N. E. Breslow (Tue,) studied this question.