Fellman J O, Eriksson A W
Folkhälsan Institute of Genetics, Population Genetics Unit, Helsinki, Finland.
Acta Genet Med Gemellol (Roma). 1990;39(3):307-16. doi: 10.1017/s0001566000005213.
In an attempt to improve our understanding of the factors that affect human twinning, we further developed the models given by Hellin (1895) and Peller (1946). The connection between these models and our own model ("Fellman's law") were studied. These attempts have resulted in a more general model, which was then applied to data from Aland Islands (1750-1939), Nmes (1790-1875), Stuttgart (about 1790-1900) and Utah (1850-1900). The product of the mean sibship size and the total twinning rate can be considered as a crude estimate of the expected number of sets of twins in a sibship. The same can be said about the twinning parameter in our model. These estimates are in good agreement. If we consider twinning data only, we obtain the geometric distribution, and log (Nk), where Nk is the number of mothers with k twin maternities, is a linear function of the number of recurrences. Graphically, this property can easily be checked. For sibships containing three or more sets of twins, all four populations show higher values than expected, particularly the populations from Stuttgart and Utah, which data also show poor agreement according to a chi 2-test. A more exact model would demand more detailed demographic information, such as distribution of sibship sizes, age-specific twinning rates and temporal variations in twinning. The observed number of mothers in Aland with several recurrences of multiple maternities shows a considerable excess over the expected number as predicted by Peller's rule. The parameters in our model can be estimated by the maximum likelihood method and the obtained model fits the data better then Peller's model.
为了增进我们对影响人类双胞胎现象的因素的理解，我们进一步完善了赫林（1895年）和佩勒（1946年）提出的模型。我们研究了这些模型与我们自己的模型（“费尔曼定律”）之间的联系。这些尝试得出了一个更通用的模型，然后将其应用于奥兰群岛（1750 - 1939年）、内梅斯（1790 - 1875年）、斯图加特（约1790 - 1900年）和犹他州（1850 - 1900年）的数据。平均同胞规模与总双胞胎出生率的乘积可被视为一个同胞中双胞胎组数预期数量的粗略估计。我们模型中的双胞胎参数也可如此。这些估计结果吻合良好。如果仅考虑双胞胎数据，我们会得到几何分布，并且log(Nk)（其中Nk是有k次双胞胎生育的母亲数量）是复发次数的线性函数。从图形上看，这一特性很容易验证。对于包含三组或更多组双胞胎的同胞群体，所有四个群体显示出的值都高于预期，特别是来自斯图加特和犹他州的群体，根据卡方检验，这些数据的吻合度也很差。一个更精确的模型将需要更详细的人口统计学信息，例如同胞规模分布、特定年龄的双胞胎出生率以及双胞胎现象的时间变化。奥兰群岛中多次出现多胞胎生育的母亲的观察数量明显超过佩勒法则预测的预期数量。我们模型中的参数可以通过最大似然法估计，并且所得到的模型比佩勒的模型更能拟合数据。
