DEMOGRAPHERS REGULARLY CALCULATE SEX RATIOS (the number of males per
100 females) for two quite different purposes. First, if they are assumed to
be accurate, they indicate the gender balance in a society. This balance is
determined by the sex ratio at birth and by sex-specific mortality and migration
over the life course. Study of the sex ratios of various age groups
allows the estimation of these demographic parameters. The measured sex
ratio at birth can be compared with a suitably selected "standard" sex ratio
reflecting known biological patterns to determine the degree to which infants
of one sex suffer excess mortality. Second, if the sex ratios are thought to
be incorrectly measured, they may be examined to determine the degree to
which one gender group is systematically undercounted in a register, survey,
or census (Johansson, 1984). In the first instance, the data can be used to
directly identify asocial problem such as gender-determined abortion or
infanticide. In the second instance, the immediate aim is to correct astatistical
error such as accidental underenumeration or concealment of information.
Identification of the sources of such errors may also reveal an underlying
bias against some individuals in a society based on their gender.
In this article, Ianalyze data from the One Percent Survey of China,
carried out by the State Statistical Bureau in 1987. The sex ratios of births
and young children calculated from these data are higher than those found
in other recent Chinese surveys and censuses and indicate a serious and
growing problem of "missing" female births. Three potential explanations
for this phenomenon are discussed below.