The Search for 100 Million Missing Women

¿Para que sirve hacer tantas regresiones? Para distinguir entre el efecto de la
misoginia y la hepatitis B…

The Search for 100 Million Missing Women
An economics detective story.
By Stephen J. Dubner and Steven D. Levitt

“(…)In an essay in the New York Review of Books, Amartya Sen claimed that
there were some 100 million “missing women” in Asia. While the ratio of men to
women in the West was nearly even, in countries like China, India, and
Pakistan, there were far more men than women. Sen charged these cultures with
gravely mistreating their young girls—perhaps by starving their daughters at
the expense of their sons or not taking the girls to doctors when they should
have. Although Sen didn’t say so, there were other sinister possibilities. Were
the missing women a result of selective abortions? Female infanticide? A forced
export of prostitutes?

Sen had used the measurement tools of economics to uncover a jarring mystery and
to accuse a culprit—misogyny. But now another economist has reached a
startlingly different conclusion.

Emily Oster is an economics graduate student at Harvard who started running
regression analyses when she was 10 (both her parents are economists) and is
particularly interested in studying disease. She first learned of the “missing
women” theory while she was an undergraduate. Then one day last summer, while
doing some poolside reading in Las Vegas—the book was Baruch Blumberg’s
Hepatitis B: The Hunt for a Killer Virus—she discovered a strange fact. In a
series of small-scale medical studies in Greece, Greenland, and elsewhere,
researchers had found that a pregnant woman with hepatitis B is far more likely
to have a baby boy than a baby girl. It wasn’t clear why—it may be that a
female fetus is more likely to be miscarried when exposed to the virus.

Oster was suitably intrigued. She set out first to see if she could use data to
confirm Blumberg’s thesis. A vaccine for hepatitis B, she learned, had been
available since the late 1970s. She found good data on a U.S. government
vaccination program in Alaska. Before the vaccinations began, Alaskan natives
had a historically high incidence of hepatitis B as well as a high birth ratio
of boys to girls. White Alaskans, meanwhile, had a low incidence of hepatitis B
and gave birth to the standard ratio of boys to girls. But after a universal
vaccination program was carried out in Alaska, the Native Alaskans’ boy-girl
ratio fell almost immediately to the normal range, while the white Alaskans’
ratio was unchanged. A vaccination program in Taiwan revealed similar results.”