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TSR Wiki > Study Help > Subjects and Revision > Revision Notes > Geography > Age Structure

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There are 3 basic age structures:

1. Progressive (Brazilian) Type
2. Stationery (American) Type
3. Regressive (European) Type

Contents 1 Progressive Type 2 Stationery Type 3 Regressive Type 4 The Dependency Ratio 5 The Old Age Index 6 Comments

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 groups 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

Comments