Mitra S
Demography. 1976 May;13(2):251-7.
The inconsistencies inherent in the one-sex models created a need for the construction of what are known as marriage functions, especially for the measurement of fertility. But attempts to develop marriage functions have been frustrated by the inability of the proposed functions to meet certain consistency conditions and also by difficulties in empiracally determining function parameters. Among several functions proposed so far, Das Gupta's (1972) "effective population" deserves special mention. He uses both sexes in its formulation, and has shown that the constancy of fertility rates based on such a function together with the constancy of survivorship probabilities of both sexes would result in a stable population. It is suggested in this article that the major source of the problem in a two-sex model seems to be the requirement that the model has to be specific both for sex and age. The ideal of incorporating the relative composition of one sex in the age-specific rates of the other, thereby creating a function dependent on both sexes, is advanced in this article. Such functions, defined explicitly for births, can be easily translated into age-specific birth rates. In addition to simplicity in the definition and form, the conditions leading toward stability can also be established. Interestingly enough, the intrinsic rate for this two-sex model lies in the interval determined by the rates obtained from the two one-sex models.
单性模型中固有的不一致性使得构建所谓的婚姻函数成为必要，特别是用于生育率的测量。但是，开发婚姻函数的尝试受到了阻碍，原因一是所提出的函数无法满足某些一致性条件，二是在经验上确定函数参数存在困难。在目前提出的几个函数中，达斯·古普塔（1972年）的“有效人口”值得特别提及。他在公式中使用了两性，并表明基于这种函数的生育率的恒定以及两性生存概率的恒定将导致人口稳定。本文认为，两性模型中问题的主要根源似乎在于该模型必须在性别和年龄方面都具有特异性这一要求。本文提出了一种理想的方法，即将一种性别的相对构成纳入另一种性别的年龄别率中，从而创建一个依赖于两性的函数。这种为出生明确定义的函数可以很容易地转化为年龄别出生率。除了定义和形式简单之外，还可以建立导致稳定的条件。有趣的是，这个两性模型的内在增长率处于由两个单性模型得出的增长率所确定的区间内。
