04

is heavily influenced by internal migration, and migrants may both have a direct impact on
criminality and is driven by factors likely related to crime such as the economic climate of
the province. Our projection uses those 2 to 27 years old in the 1990 census, where the
16-25 sex ratio in say, Sichuan province in 1988 is calculated as the sex ratio among those
18 to 27 year old in Sichuan in the 1990 census. On the other end, the sex ratio of 16-25
years old in Sichuan in 2004 is calculated as the sex ratio of those 2-11 years old in the 1990
census. These projected sex ratios likely reflect the sex ratios at birth fairly closely for two
reasons. First, internal migration was heavily regulated until the early 1990s. Second, even
with a so called floating population estimated in hundred millions, migration before age 16
is negligible according to the data in the 2000 census.6 Nonetheless, as a falsification test,
we use the 2000 census to project sex ratios that would reflect actual sex ratios (inclusive
of domestic migration) more closely, and we find that this sex ratio