 Solution

The Fort Worth observation for ages 75–84 is missing. It is not a zero count and cannot be replaced by one. The missing cell prevents a direct two-city comparison in that age group and leaves an unbalanced age-by-city table. The youngest groups have only one and four cases, so chi-squared asymptotic approximations to tests and uncertainty may be poor there. The open-ended oldest group and broad age bands can conceal different within-group age compositions between cities.

The denominators are population counts rather than reported person-time, and the observation period is not specified. Comparable coverage, case definitions and time periods must therefore be established before interpreting the numbers as comparable incidence measures. The data contain no information on potential confounders such as individual risk factors or differences in ascertainment. These are aggregated observations on women in the listed ages, and any fitted city association is not automatically causal or generalizable beyond that population.