The Measurement of Wanted Fertility
Citation: Bongaarts, John (1990) The Measurement of Wanted Fertility.
Estimates of wanted fertility are of interest because they provide an indication of the extent to which fertility would be reduced if women were completely successful in implementing their preferences for stopping childbearing. Wanted fertility is not a pure preference measure, however, because it is affected by behaviors and other factors that are not directly related to family size preferences. 1. Desired family size Biases of the measure: rationalization; non-numerical responses; "voluntary" limitation of fertility (some women report ideal size instead); infant and child mortality; compositional preferences; involuntary limitation of fertility(subfecund marital dissolution, non-marriage; changes in timing of childbearing 2. Wanted status of recent births Biases: rationalization 3. Desire for additional children Biases: rationalization 4. Bongaarts' (199)) estimate: First, the so-called want-more TFR is calculated. This equals the proportion of the TFR attributable to births among women who want more children at the time of the survey (i.e, the TFR that results after deleting births to women who want to stop childbearing)/ This want-more TFR is relatively simple to calculate, but it significantly underestimates the true wanted TFR because some of the births to women who wish no more children at the time of the survey were wanted at the time they occurred. There are 3 groups (a) wanted births to women who want more at the time of survey; (b) wanted births to women who want no more; and (c) unwanted births to women who want no more. This asuumes that all births are wanted before a woman changes status from wanting more to wanting no more, and that births occurring to women after they desire to stop childbearing are unwanted. The want-more TFR includes only births in category (a). The second step consists of estimating the part of the TFR that is attributable to births in category (b). This part equals one birth per woman if: all women achieve their wanted family size; all women want at least one birth; there is no time trend in wanted fertility; and the reference period for which the wanted TFR is calculated is sufficiently short to include only one birth per woman. Under these conditions, the wanted TFR (WTFR) = the want-more TFR (WMTFR) + 1 c (proportion of all married women in the age group 40-44 who want more children).