Cases of disease or other health-related information reported to our surveillance system can also be characterized by gender. In this example, rather than a disease, let’s look at a health promotion behavior, daily vitamin A intake among pre-school children. We see that slightly over a third of children had adequate daily intakes of vitamin A. In addition, assuming the population included nearly equal numbers of female and male children 1-4 years of age, the data suggested that less than one-quarter of girls received adequate levels of vitamin A while over half of boys had sufficient vitamin A intake. This data led us to ask why this difference existed, and to reexamine our data, this time cross-classified by gender and age group.