MAXIMUM (MAX) AND MID-P-CONFIDENCE-INTERVALS AND P-VALUES FOR THE STANDARDIZED MORTALITY AND INCIDENCE RATIOS

The authors present algorithms to compute the confidence interval for a Poisson parameter (lambda) and the p value for testing the hypothesi s that lambda is equal to a constant, which can be used to make infere nces about the standardized mortality ratio and the standardized incid ence ratio. The p value and confidence interval always agree, despite the discrete nature of the Poisson distribution. The authors also give simple equations to compute numeric approximations of the confidence limits that do not require the use of any probability distributions. A n example based on data arising from a study of cancer incidence is gi ven.