In a 2013 TED talk Peter Singer claims
“It costs about 40,000 dollars to train a guide dog and train the recipient so that the guide dog can be an effective help to a blind person. It costs somewhere between 20 and 50 dollars to cure a blind person in a developing country if they have trachoma.”
Unfortunately, this claim is not accurate. To begin with, blindness from trachoma is irreversible so it's only possible to prevent blindness from trachoma, not to cure it. According to a GiveWell blog post, it does cost ~$20-60 to perform one trachoma surgery but “there can be a small improvement in vision following surgery”. According to their back-of-envelope calculation with some assumptions, 1 case of full-blown blindness is averted for every 6-20 successful surgeries. In any case, my point is that people who use this example to advertise GiveWell don't read what GiveWell has to say about it.
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EDIT (2017-05-16): Even though GiveWell haven't made such claim and may have a different opinion, one doctor (who has a much deeper understanding of these issues than me) commented that she "would be comfortable with saying that for about $100 we can prevent trachoma-induced blindness" and that Singer's claim was not as nearly as inaccurate as I made it seem.
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As of 2017-05-10, Giving What We Can also gives a similar example:
“In the developing world there are more than a million people suffering from trachoma-induced blindness and poor vision which could be helped by a safe eye operation, costing only about $100 and preventing 1-30 years of blindness and another 1-30 years of low vision, according to GiveWell.org”
They also do something EAs (including me) don’t do often enough — provide a source. The source is a GiveWell page which is published in 2009 and has a disclaimer
“The content on this page has not been recently updated. This content is likely to be no longer fully accurate, both with respect to the research it presents and with respect to what it implies about our views and positions.”
The page has the following text:
“We have not done thorough cost-effectiveness analysis of this program. Because such analysis is highly time-consuming - and because the results can vary significantly depending on details of the context - we generally do not provide cost-effectiveness analysis for an intervention unless we find what we consider to be a strong associated giving opportunity.
We provide some preliminary figures based on the Disease Control Priorities in Developing Countries report, which we previously used for cost-effectiveness estimates until we vetted its work in 2011, finding major errors that raised general concerns.
We have relatively little information about the likely impact of this program, so it's difficult to estimate the cost-effectiveness.”
[...]
“Using a simple conversion calculation, we estimate that $100 prevents 1-30 years of blindness and an additional 1-30 years of low vision when spent on surgeries (though insignificant benefits, in these terms, when spent on antibiotics). The source of the Disease Control Priorities in Developing Countries report's estimate is unclear and these figures should be taken with extreme caution.”
It seems unfair to just provide the numbers and skip all these disclaimers. Despite knowing about this uncertainty, sometimes I feel temptation to also omit disclaimers and just present the numbers to be more convincing. After all, the goal is very admirable - to help more people living in extreme poverty. But I believe that in the long run EA will achieve more if we are being totally honest and upfront about uncertainties and never take any shortcuts. Otherwise we might not be trusted the next time we have something to say. Furthermore, to influence the world we need our community to have a correct model of the world.
On the other hand, trachoma is a horrible disease. Just watch this excerpt:
tl;dw: eyelids turn inwards and eyelashes scrape the eyeball, causing intense pain on every blink. That scraping eventually causes blindness. People treat themselves by pulling out their eyelashes with tweezers. One woman said she does it every 2 weeks. Horrible.
If you worry about being convincing, you can talk about that and then honestly talk about uncertainty regarding numbers. Most people are scope insensitive anyway. Or you can talk about cataract surgery instead of trachoma because disclaimers in this page seem slightly less severe. Or just talk about your favorite charity and then add "imagine that suffering could be prevented so cheaply in our country, action would be taken urgently". But the main points of this post are
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many of us were overstating the point that money goes further in poor countries
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many of us don’t do enough fact checking, especially before making public claims
- many of us should communicate uncertainty better
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EDIT (2017-05-15):
Many people in the comments gave other reasons not to use the comparison but if you decide to use it anyway and want to quote GiveWell, you could also use figures from this Peter Singer's comment. Alternatively, you can use one of the other comparisons proposed by Ben Todd.
This feels like nitpicking that gives the impression of undermining Singer's original claim when in reality the figures support them. I have no reason to believe Singer was claiming that of all possible charitable donations trauchoma is the most effective, merely to give the most stunningly large difference in cost effectiveness between charitable donations used for comparable ends (both about blindness so no hard comparisons across kinds of suffering/disability).
I agree that within the EA community and when presenting EA analysis of cost-effectiveness it is important to be upfront with the full complexity of the figures. However, Singer's purpose at TED isn't to carefully pick the most cost effective donations but to force people to confront the fact that cost effectiveness matters.. While those of us already in EA might find a statement like "We prevent 1 year of blindness for every 3 surgeries done which on average cost..." perfectly compelling the audience members who aren't yet persuaded simply tune out. After all it's just more math talk and they are interested in emotional impact. The only way to convince them is to ignore getting the numbers perfectly right and focus on the emotional impact of choosing to help a blind person in the US get a dog rather than many people in poor countries avoid blindness.
Now it's important that we don't simplify in misleading ways but even with the qualifications here it is obvious that it still costs orders of magnitude more to train a dog than prevent blindness via this surgery. Moreover, once one factors in considerations like pain, the imperfect replacement for eyes provided by a dog, etc.. the original numbers are probably too favorable to dog training as far as relative cost effectiveness goes.
This isn't to say that your point here isn't important regarding people inside EA making estimates or givewell analysis or the like. I'm just pointing out that it's important to distinguish the kind of thing being done at a TED talk like this from that being done by givewell. So long as when people leave the TED talk their research leaves the big picture in place (dogs >>>> trauchoma surgery) it's a victory.
I hate to admit it, but I think there does exist a utilitarian trade-off between marketability and accuracy. Although I'm thrilled that the EA movement prides itself on being as factually accurate as possible and I believe the core EA movement absolutely needs to stick with that, there is a case to be made that an exaggerated truth may be an important teaching tool in helping non-EAs understand why EAs do what they do.
It seems likely that Peter Singer's example has had a net-positive impact, despite the inaccuracies. Even I was originally drawn to EA... (read more)