Missing girls and the One Child Policy

So I was looking at the Chinese census data out of curiosity, since I wanted to guess how many “missing girls” and missing babies in general were not born or disappeared due to the One Child Policy.

First of all, the stats actually suggest that girl births and the fertility rate increased slightly in the 80s, and didn’t fall to sub-replacement until about late 1990. The sex ratio for people born in the mid to late 80s actually appears to be lower and more female than for Chinese people born prior to 1980, which surprised me!

My guess here is that the One Child Policy was not widely or actively enforced on a large scale until after Tiananmen Square, because the immense fall in Chinese births in 1990-91 suggests that in the second half of 1989 people were suddenly choosing (or being forced) to have fewer kids, and I’d assume, abort daughters at a higher rate than sons.

Otherwise it’s impossible to explain how the Chinese birth rate could have fallen from 2.6 in 1990 to 1.4 in 1997. It’s true Chinese society was changing very fast, but not enough that people would willingly have so many fewer kids in such a short amount of time.

The one-child policy could indeed lead to a higher proportion of girls, though only indirectly. In rural areas, if your first child was a daughter, you could get an exemption to the policy to try again for a son. Now, if the odds for every child were independent, this wouldn’t matter: You’d get half of all families with one son, a quarter with one of each, and a quarter with two daughters, for a total of three sons and three daughters per four families. But the odds for each child probably aren’t independent. In the real world, there are probably some parents that are more likely to have daughters, and some that are more likely to have sons, for a variety of reasons. Those two biases normally tend to balance out, but if it’s only the families with a daughter that get to try again, then on average, the female-inclined parents will tend to have more kids than the male-inclined parents.

The drop in fertility is easily explained. There has been a MASSIVE movement from rural to urban. Like western society, children in a city in China are not productive, nor are they cheap. Like here, they cut into the mother’s ability to provide a second income, or cost money for day care.

(In an story about the one child policy relaxation, someone mentioned that for 2 years now there’s been an exemption if both parents were single children, yet only about 6% have chosen a second child. One local mentioned that the fancy “prep school” for good college and a good job could run up to $20,000 a year.)

That would be an erroneous assumption. One child policy was draconian enforced since the late 1970’s. Correlation with Tiananmen does not lead to causation.

As mentioned above, the migration/relaxation of tying peasants/household registration (“hukou”) to the countryside is the driving factor.

Yes, but I don’t see how this could lead to such a drop in fertility within a single year.

Also - why did the sex ratio skew in favor of males in the 60s and 70s, fall to around normal in the late 70s/early 80s and go haywire in favor of boys after 1985?

It only ever applied to 36% of the population anyway.

To a first approximation, the probability for each birth is independent. To the extent that it’s not, as Chronos described, it’s a positive correlation, which would tend to increase the proportion of girls in the Chinese social dynamic.

Therefore, the only mechanisms to explain the unusual sex ratio are:
(i) The statistics are wrong - underreporting, hiding girl births;
(ii) Infanticide;
(iii) Sex-selective abortion.

Sex-selective abortion (through ultrasound) was not available in China prior to the 1980s.