The GiveWell Blog

Questioning the evidence on hookworm eradication in the American South


  • Four of GiveWell’s top charities support deworming—the mass distribution of medicines to children in poor countries to rid their bodies of schistosomiasis, hookworm, and parasites.
  • GiveWell’s recommendation relies primarily on research from western Kenya finding that deworming in childhood boosted income in adulthood. GiveWell has also placed weight on a study by Hoyt Bleakley of the hookworm eradication effort in the American South 100 years ago.
  • I reviewed the Bleakley study and reach a different conclusion than he did: the deworming campaign in the American South did not coincide with breaks in long-term trends that would invite eradication as the explanation.
  • GiveWell research staff took the conclusions of this post into account when updating their recommendations for the 2017 giving season. GiveWell continues to recommend deworming charities.
  • I also reviewed a separate Bleakley study of the impacts of malaria eradication in the United States, Brazil, Colombia, and Mexico. My reading there is more supporting. I’m finalizing the write-ups now and will share them soon.

How thin the reed? Generalizing from “Worms at Work”

Hookworm (AJC1/flickr) My last post explains why I largely trust the most famous school-based deworming experiment, in particular the report in Worms at Work about its long-term benefits. That post also gives background on the deworming debate, so please read it first. In this post, I’ll talk about the problem of generalization. If deworming in southern Busia… Read More

Why I mostly believe in Worms

The following statements are true: “GiveWell is a nonprofit dedicated to finding outstanding giving opportunities through in-depth analysis. Thousands of hours of research have gone into finding our top-ratepd charities.” GiveWell recommends four deworming charities as having outstanding expected value. Why? Hundreds of millions of kids harbor parasitic worms in their guts[1]. Treatment is safe,… Read More

Why a new study of the Mariel boatlift has not changed our views on the benefits of immigration

As a consultant for the Open Philanthropy Project last year, I reviewed the research on whether immigration reduces employment or earnings for workers in receiving countries. I concluded that for natives the harm, if any, is small. Last month the prominent immigration researcher George Borjas posted a challenge to a seminal study in my review. His new paper contends that the Mariel boatlift, which brought some… Read More

Coming down to earth: What if a big geomagnetic storm does hit?

This is the fourth post in a series about geomagnetic storms as a global catastrophic risk. A paper covering the material in this series was recently released. I devoted the first three posts in this series to describing geomagnetic storms and assessing the odds that a Big One is coming. I concluded that the iconic Carrington… Read More

Could raising alcohol taxes save lives?

I’ve just posted a review on the effects of alcohol taxes on alcohol consumption—and on the lives that alcohol abuse can cost. This literature review is unusual in the degree to which it replicates the studies it examines, so I have called it a “replication review.” Data, code, and spreadsheets are here. The literature on… Read More