Last May I thought I had found “75 percent of the missing women in China,” but new research done by Ming-Jen Lin and Ming-Ching Luoh at National Taiwan University seems to have cast serious doubt on Emily Oster’s work. As a result, those women are now missing again.
Here is the abstract of Lin and Luoh’s paper:
Using novel data from the National Hepatitis B Immunization Program in Taiwan, this study attempts to contribute to this issue by investigating three million births in Taiwan and the HBsAg status of the mothers at the time of the pregnancy. We demonstrate that the marginal probability of an HBsAg(+) mother having a male birth is only 0.0025. … Given that 15 percent of all mothers are infected with HBV, the disease can only raise the sex ratio from a baseline of 105 to 105.165. We therefore conclude that the effect of HBV mothers on sex ratio among their offspring is minimal, and hence can account for only a small portion of the case of missing women.
Ming-Jen Lin was a student of Freakonomics author Steven Levitt at Chicago.