A population pyramid graphically displays the age by sex data of a community at one point in time. The graph helps to easily see the age distribution of both males and females at a glance. It is also a very visual way to compare the community you are studying to another community to the state. Bars allow the student to easily identify and compare relationships within a variable, by using a graphic representation of the number of cases per interval. The length of the bar is proportional to the number of cases in the interval.
Population pyramids show the relative size of each age and sex category.
The pyramids in Figure 1 are drawn to a uniform scale in order to illustrate the growth in the size of the population. The distance between each vertical line in Figure 1 represents 100,000 persons. The population in both the old and new federal states began to decline in the 1970s because the birthrate was falling. Since 1990, however, there has once again been a slight upward trend in the west. Germany nevertheless has one of the lowest birthrates in the world.