Furthermore, Klasen and Wink noted that both Sen's and Coale's methodologies were flawed because Sen and Coale assume that optimal sex ratios are constant across time and space, which they are often not.
Klasen dan Wink mencatat bahwa metodologi Sen dan Coale cacat karena Sen dan Coale berasumsi bahwa rasio seks yang optimal konstan sepanjang waktu dan ruang, yang seringkali tidak mereka rasakan.