Wide base = high birth rate Narrow base = falling birth rate Concave shape = high death rate Convex shape = low death rate
The percentages of females to males should be relatively the same (symmetrical)
Moving upwards, the percentage of females will be greater due to higher female life expectancy
zz A-Z
Demographic anomaly: When the expected population pattern does not occur.
A bulge in the side shows a demographic anomaly, for example, baby boom, impact of migration (Fig. 25.14)
Male United Arab Emirates 2016
Fig. 25.14 Population Pyramid, United Arab Emirates. This pyramid shows an anomaly in the ratio of males to females. Total males between 20 and 54 far exceed female totals. The large number of male migrant workers present in the country explains this.
0 0.6 Population (in thousands) Age group Uses of population pyramids
Governments and local authorities use population pyramids to predict healthcare requirements for the elderly and demand for housing and schools, and to inform taxation policy to cope with increasing dependents.
CHECK YOUR LEARNING
Study Figure 25.15 and answer the following questions:
1. Which gender is the largest in the over 70s group?
2. Suggest a reason for this. 3. Overall, which age group is the largest?
4. Suggest reasons why the 20–24 age group has declined.
430 215 172 129 86 43 0 0 Population (in thousands) Age group 43 86 129 172 215 Population (in thousands) Female 1.2 1.8 2.4 3 Population (in thousands) Female
