Age Structure Diagrams

Age Structure Diagrams: visual representations of age structure within a country for males and females

population pyramid: wider at the bottom and smallest at the top

population momentum: when they try and reduce birth rates so that it catches up with the growing population

What is likely to happen to the population?

Eventually over several generations those actions will bring the population to a more stable-growth rate.

Population Calculations

Calculate birth and death rate

r= CBR-CDR/10

Calculate growth rate

global pop. growth rate= CBR-CDR/10

nation pop. growth rate= (DBR+immigrants)-(CDR+ emigrants)/10

Calculate doubling time

Doubling time (in years)= 70/growth rate

Phases of demographic transition

What are they?

What is happening to cause the changes in phases?

Phase 1: Slow (pre industrial)population grows very slowly because of a high birth rate and a high death rate

represents a population that is nearly at steady state

infant number is low because of disease(AIDS), adults short lifespan because of difficult working conditions

Phase 2: Rapid (transitional)population grows rapidly because birth rates are high and death rates drop

death rates decline while birth rates remain high and as a result the population