Age Structure

Age Structure


* There are 3 basic age structures:
1. Progressive (Brazilian) Type
2. Stationery (American) Type
3. Regressive (European) Type

Progressive Type

* It has a wide base that quickly narrows upwards to a point.
* It indicates a large birth rate, but poor conditions mean people rapidly die off, hence the triangular shape of the structure. The population is increasing.
Stationery Type
* The shape of this structure is more "square." All age roups are well represented.
* It indicates that the birth rate is moderate, and few people die off as they get older. The population is stagnant.
Regressive Type
* The structure has a fairly wide top with a bulging middle and narrow base.
* The birth rate is low, hence the low base, and there are more adults than children. The population is decreasing.
The Dependency Ratio
* This is the ratio between the non-working population (children and aged) and the workers (adults).
* It is lowest in regressive populations and highest in progressive populations.
* It is calculated using the formula (children + aged)/Adults) * 100
* In developed countries, the DRs range from 50-70. In most developing countries the DRs are over 100
The Old Age Index
* This is the proportion of aged to adults.
* It is calculated using the formula: (aged)/(adults) * 100