# Tempo-adjusted total fertility rate

## Definition

The term **adjusted total fertility rate** or **tempo-adjusted total fertility rate** refers to a modified form of the total fertility rate that accounts for the tempo effect in a manner that provides (arguably) a better estimate of the completed fertility rate in the long term.

The standard definition of total fertility rate is that it is the sum of the age-specific fertility rates for all ages. Alternatively, it is the number of live births a hypothetical woman would have if she passed through her childbearing years conforming to the age-specific fertility rate of this particular year. If age-specific fertility rates hold constant over time, i.e., in the absence of tempo effects, the total fertility rate would equal the completed fertility rate for a birth cohort of females who have completed their childbearing years.

In the presence of tempo effects, we expect that age-specific fertility rates will change over time. The *tempo-adjusted* total fertility rate attempts to use data measuring the number, nature, and temporal distribution of live births *in the current year and immediately surrounding years*.

### Bongaarts-Feeney formula

The formula works as follows. We will denote by the year for which we are attempting to estimate the tempo-adjusted total fertility rate. We assume that we have data for years and . Further, we assume that the data we have is sufficient to compute not only the age-specific fertility rates, but the age-specific fertility rates broken down based on birth order.

We provide a hierarchical breakdown of the computation of the formula:

- We compute the tempo-adjusted total fertility rate as the sum, over all possible birth orders, of the tempo-adjusted total fertility rate
*for that birth order*. - For each birth order , we compute the tempo-adjusted total fertility rate
*for that birth order*as the product of the total fertility rate*for that birth order*and an adjustment factor.- The total fertility rate for that birth order is defined as the sum of the age-specific fertility rates for that birth order.
- The adjustment factor is defined as where is the rate of change of mean age of childbearing for birth order . Explicitly, is estimated as the half-difference between the mean age of childbearing values for the next year and the previous year: . Here denotes the mean age of childbearing at birth order .

Overall, the formula is:

where:

where:

(with the right side denoting summation over age-specific fertility rates at a given birth order)

and:

## Values

### Most recent values

Values here are based on the Human Fertility Database, a highly reliable source, but one that is limited to a few countries.

Country | Fertility information | adjTFR (2009) | adjTFR (2008) | adjTFR (2007) | adjTFR (2006) |
---|---|---|---|---|---|

Japan | Fertility in Japan | unavailable | 1.512 | 1.474 | 1.476 |

Germany | Fertility in Germany | unavailable | unavailable | unavailable | unavailable |

Russia | Fertility in Russia | 1.822 | 1.731 | 1.579 | 1.45 |

USA | Fertility in USA | 2.349 | 2.294 | 2.242 | 2.119 |

Taiwan | Fertility in Taiwan | 1.559 | 1.543 | 1.602 | 1.668 |

Sweden | Fertility in Sweden | 2.078 | 2.016 | 1.94 | 2.023 |

Canada | Fertility in Canada | unavailable | 1.799 | 1.747 | 1.728 |