Specific mistakes

  • p. 3: Two damning reports were released, one by UNICEF and one by the Swiss Resource Centre and Consultancies for Development (SKAT).
    Although the first report carries the UNICEF logo on its cover, it was not approved by UNICEF. Vanesa Tobin, from UNICEF, clarifies in a private letter forwarded to me by Colin Morris, Director of Roundabout Water Solutions: "The report is based on pre-assessment field visits as part of a joint World Vision/UNICEF internal review conducted in August 2007. However, the UNICEF report was issued erroneously. It is UNICEF practice to share draft assessment reports with all concerned parties for their comments prior to issuing a final report. This was not done."
  • p. 41: The primary recipient of the Fistula Foundation's revenue is the Hamlin Fistula Hospital in Addis Ababa, Ethiopia.
    I had intended this sentence to refer to the Fistula Foundation as of 2009, when the story I was telling was set. However, I understand it could easily be interpreted as referring to the Fistula Foundation now, in which case it would be inaccurate. An accurate and unambiguous sentence would be: "In 2009, the primary recipient of the Fistula Foundation’s revenue was the Hamlin Fistula Hospital in Addis Ababa, Ethiopia." The reasons I did not in 2009 think that the Fistula Foundation was the most cost-effective charity had nothing to do with the size of the charity or the locations it operated in, but instead were to do with the cost per fistula surgery.
  • p. 61: The figure for Kaposi's sarcoma should be 0.02, not 0.2. (This typo appears only in early printings of the UK edition.)
  • p. 141[Bailey Norwood] rates beef cattle at 6 and dairy cows at 4. In contrast his average rating for broiler chickens is –1, and for pigs and caged hens is –5.
    Norwood's estimates are found on Table 8.2 (p. 229) of Compassion, by the Pound (Oxford: Oxford University Press, 2011):

My first sentence above correctly reports Norwood's welfare scores for the corresponding market animals, but the figures in the second sentence are mistaken. This mistake doesn't affect my conclusions about pork and egg consumption, but it does have implications for what I say about chickens. While Norwood believes that breeder chickens have negative lives (-4), he thinks that the lives of market chickens are positive (3). And because market chickens outnumber breeder chickens by more than two orders of magnitude, these estimates imply that demand for chicken meat increases animal welfare overall. This contradicts my claim, found on p. 142, that cutting chicken from one's diet is an effective way of reducing animal suffering.
While I'm in general happy to defer to Norwood's expertise, I think that his specific estimates for chickens are at odds with the available evidence, which to me strongly suggests that chickens should be given a negative score. I therefore stand by the recommendations in my book, despite the fact that they are not supported by Norwood in this particular instance. Readers interested in forming their own opinion are encouraged to take a look at this report from the Humane Society of the United States, which is the best discussion of these issues that I was able to find, as well as this exchange between Norwood and researcher Simon Knutsson (on the assumptions behind Norwood's estimates) and this chapter from Nick Cooney's Veganomics (featuring an alternative estimate by animal welfare expert Sara Shields).
(I thank Avi Norowitz for kindly bringing this error to my attention.)

  • pp. 144-5: However, the subjects were told that, whether or not their answers were correct, they'd be paid five cents every time they indicated there were more dots on the left-hand side of the line and five cents every time they indicated there were more dot on the right hand side.
    The boldfaced text should be: 0.5 cents.
    (I thank Mitch Trachtenbergfor kindly bringing this error to my attention.)
  • p. 169:  With an economics PhD from Harvard, the founder [of GiveDirectly], Paul Niehaus, had very good earning-to-give options.
    GiveDirectly was co-founded by Paul Niehaus, Michael Faye, Rohit Wanchoo and Jeremy Shapiro, not founded by Paul Niehaus alone as the above sentence implies.

General comments

  • Deworming.
    In the book, I claimed that deworming programs significantly improve school performance and attendance, and provide considerable health and economic benefits (pp. 8-9). The first of these claims was based on Miguel and Kremer 2004, a widely cited randomized trial of deworming. This analysis has been the subject of some considerable debate. In my framing of deworming, I could have been clearer that the extent of the benefits of deworming are still uncertain: the key argument for deworming is that it's exceptionally cheap, and it's at least highly plausible, given what we know, that there are very significant benefits, not that it's certain that there are very significant benefits. (This is enough for deworming to be an outstanding program: If you had a dozen worms living in your stomach, and there was a $0.50 pill that could kill them, giving you a good chance - but not a guarantee - of significantly greater earnings later in life, would you do so?). I could also have been clearer that the most robust evidence in favour of deworming regards its long-term benefits in terms of increased productivity and increased earnings, rather than short-term benefits in terms of school attendance. This is explained in more depth by GiveWell and Giving What We Can in two blog posts discussing the issue; my views are largely the same as those given in those blog posts.
  • PlayPump.
    Although I stand by my assessment of the PlayPump in the Introduction of the book, readers may be interested in taking a look at this response letter by Colin Morris, Director of RoundAbout Water Solutions (published here by kind permission of Mr Morris).