Parity progression ratios

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A parity progression ratios (PPR) is a measure commonly used in demography to study fertility. The PPR is simply the proportion of women with a certain number of children who go onto have another child. Calculating the PPR, also known as a_{x}, can be achieved by using the following formula:

a_{x}={\text{(women with at least }}x+1{\text{ children ever borne) }}/{\text{ (women with at least }}x{\text{ children ever born)}}[1]

In more developed countries where two child families are seen as the norm a_{2} (or the proportion of women with two children who go on to have a third) is of critical importance in determining overall fertility levels.

a_{0} is simply the proportion of women who become mothers.

References

  1. Hinde, A (1998) "Demographic Methods", Hodder Arnold Publication.
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