Should SIRs be used to compare one communitys cancer rates to another communitys cancer rates?
No. Comparison of SIRs between communities or census tracts is an inappropriate use of the statistic. Such comparisons are inappropriate because the age distribution or structure of a community has a strong effect on its cancer rates and no two communities have the same age distributions within their populations. An SIR, which is based on a community’s age distribution as well as the state’s, can appropriately be used to evaluate whether a community’s cancer incidence rates differ from those of the state as a whole.
