A topic of some interest in the genetic literature over at least the past 30 years has been the study of sexratio data. In particular, one suggested hypothesis is that there are enough families with a preponderance of males (females) that the sexes of successive childbirths are not independent random variables but rather are related to each other. This hypothesis has been extended beyond just successive births, so some authors also consider relationships between offspring two birth orders apart (first and third offspring, second and fourth offspring, etc.). Sex-ratio data from the first 5 births in 51,868 families are given in Data Set SEXRAT.DAT (at www.cengagebrain.com). The format of this file is given in Table 4.18 [10]. What are your conclusions concerning the preceding hypothesis based on your analysis of these data?

Table 4.18: Format of SEXRAT.DAT

Variable _________________________ Column
Number of childrena ............................ 1
Sex of childrenb ............................... 3−7
Number of families ........................ 9−12

^aFor families with 5+ children, the sexes of the first 5 children are listed. The number of children is given as 5 for such families.
^bThe sex of successive births is given. Thus, MMMF means the first 3 children were males and the fourth child was a female. There were 484 such families.