PAPP101 - S03: How demographers think about populations: age and sex

Sex ratios

Although population pyramids show the relative numbers of men and women in the population, it is more common to use sex ratios as a summary measure.

Sex ratios give the number of men for every woman in the population. It is calculated as follows:

sex ratio =	total number of men
	total number of women

This figure is often multiplied by 100 to give the number of men in the population for every 100 women.

Sex ratios may be calculated for the total population or by age group. As you will see, the sex ratio is strongly related to age and so calculation by age group is often more useful as the sex ratio for the total population obscures important variation.