Multiplicative Poisson models with unequal cell rates.

A two way frequency table with independent Poisson distribution cell numbers is considered. The expected number in each cell is a product of a row effect, a column effect and a known constant. Methods are developed for estimation of the parameters by maximum likelihood. In addition, asymptotic X²-tests are considered for checking the model and testing equality of column effects and/or row effects. The proposed method is applied to Danish lung cancer data.