Suchindran C M, Koo H P
University of North Carolina, Department of Biostatistics, Chapel Hill 27599-7400.
Demography. 1992 May;29(2):227-45.
This paper examines the ways in which the behavior of twentieth century cohorts of American women changed simultaneously in the three components of fertility that determine age at last birth--age at first birth, spacing between subsequent births, and parity progression ratios of subsequent births--to produce changes in the timing of the completion of childbearing. It decomposes changes in the mean age at last birth among cohorts and between whites and nonwhites to changes in these three components. To perform these analyses, we developed and applied a method to estimate the distributions and means of ages and last births, birth intervals, and parity progression ratios from age- and parity-specific fertility rates available from vital statistics data. Results show that the cohorts increased and decreased their age at first birth, birth intervals, and parity progression ratios of lower and higher birth orders in almost every possible combination so as to achieve a relatively young age at final birth.
本文研究了20世纪美国女性群体的行为在决定最后生育年龄的生育三个组成部分（初育年龄、后续生育间隔以及后续生育的胎次递进比例）中同时发生变化的方式，这些变化导致了生育完成时间的改变。它将不同群体之间以及白人与非白人之间最后生育平均年龄的变化分解为这三个组成部分的变化。为了进行这些分析，我们开发并应用了一种方法，根据生命统计数据中按年龄和胎次划分的生育率来估计年龄和最后生育情况、生育间隔以及胎次递进比例的分布和均值。结果表明，几乎在每一种可能的组合中，不同群体都增加和减少了她们的初育年龄、生育间隔以及高低不同胎次的胎次递进比例，以便在最终生育时达到相对年轻的年龄。
