The Total Fertility Rate (cont.)
Period table with cohort example (cont.)
The table below is the same table as on the previous page but we are going to look at it a different way. The period TFRs are easily calculated for each calendar period. If we have enough data, which we do here, we can also look for cohort measures.
How would we identify a cohort? Think about this and then press the button underneath the table to reveal a cohort within these data.
Table 2: Age-specific fertility rates, England and Wales, by calendar period.
The thinking behind this is as follows: The 15-19 age group in 1960-64 have a particular ASFR. In 5 years time it will be 1965-69 and they will all be 20-24 – and we can read off their ASFR at that age/period – and so on. Note that this is not necessarily a true cohort – we don’t know that they are the very same people moving from period to period, but if the data are based on either the whole population, or a representative sample, then we can assume that the same group are being represented as they age.
The Cohort Fertility Rate will be 2.18.
