Population structures. Flashcards
Dependency ratio.
Shows the relationship between the economically active population and the non-economically active population.
Support ratio.
This is the inverse of the dependency ratio.
Juvenility index.
This shows the proportion of the dependency ratio.
Old-age index.
This shows the proportion of elderly people in a population.
Pyramids show….
- The results of births minus deaths in specific age groups.
- The effects of migration (if regional or local scale).
- The effects of events such as war, famine and disease (possibly).
- An indication of the overall life expectancy of a country.
Stage 1 (high fluctuating).
- Birth rate is high so a wide base.
- Death rate is high so concave sides.
- Life expectancy is low so a short pyramid.
Stage 2 (early expanding).
- Birth rate is still high so a wide base.
- Death rate is falling, so sides become more triangular and
fill out
. - Life expectancy is slightly higher so the pyramid is a bit taller.
Stage 3 (late expanding).
- The birth rate begins to fall, so the base is narrower.
* Death rates, including Infant mortality rates, continue to fall so the sides are more convex.
Stage 4 (low fluctuating).
- Birth rates are low so the base is narrow.
- Death rates are low so the sides are more convex or vertical.
- Life expectancy is higher so the pyramid is taller.
- There is a more balanced age structure.
Stage 5 (decline).
•As above, but the pyramid may now wider at the top and taller indicating an Ageing population structure and longer life expectancy.