Fertility quantum and tempo with cubic age-specific birth rates

Fertility quantum and tempo with cubic age-specific birth rates

Blog Article

OBJECTIVE: To demonstrate the analytical value of a cubic parameterization of the age curve of fertility and to explore its features, especially its usefulness in separating fertility level and fertility timing.METHODS: Using mathematical analysis, the cubic fertility curve is derived and examined in both continuous and discrete forms.RESULTS: The cubic curve for replacement level fertility is found and expressed in terms of the mean age of fertility.That baseline cubic birth rate density, proportionately adjusted for T Shirt the level of fertility, is shown to plausibly fit observed birth rates and imply a new approximation for their implicit stable growth rate.Because the proposed cubic model separates the effects of fertility level (quantum) and fertility timing (tempo), it leads to new period/cohort and population momentum relationships and provides a structure for relating fertility trajectories to birth sequences in changing rate models.

CONTRIBUTION: The cubic parameterization can simplify the representation of age curves of fertility rates while capturing their essential features.With a proportional adjustment at all ages to reflect fertility level, the cubic model can separate level and timing effects and permit numerous analytical Tape applications.Of note, those applications include a new and superior approach to how changes in period tempo with constant quantum affect cohort fertility.