We use averages because they are useful for comparing differing quantities of the same category. For example, to compute the per capita income of a country, averages have to be used because there are differences in the incomes of diverse people. However, there are limitations to the use of averages. Even though they are useful for comparison, they may also hide disparities. For example, the infant mortality rate of a country does not differentiate between the male and female infants born in that country. Such an average tells us nothing about whether the number of children dying before the age of one are mostly boys or girls.