I agree on a meta level that the section on contraception shouldn’t be here.
On the object level, this isn’t the first time I’ve seen a charity analysis make the assumption that a problem can be completely solved if you multiply “cost to solve X% of the problem” by 100/X. This seems unlikely to be true in most cases, and is an important mistake to avoid.
For example, even if Guttmacher is correct that $9.4 billion will allow us to meet all unmet demand for contraceptives, contraceptives aren’t always used correctly, and even when used correctly, they don’t always work, so we won’t stop all 74 million unintended pregnancies. Also, not every unintended pregnancy leads to a child being born. And I suspect (from a brief skim of the report, I could be wrong here) that the $9.4 billion number involves some basic multiplication on Guttmacher’s part, without fully accounting for how difficult it is to reach different populations (in communities where contraceptives are forbidden, how much will it cost to change that policy?).
It’s still valuable to estimate and round, but the “multiply the number of people by the cost per person” fallacy (is there a catchier name?) seems like it routinely underestimates the cost of fully “fixing” a problem for reasons like these: Some % of your target population is hard to reach, and the thing that you think will always fix the problem only fixes it some % of the time.
Aaron, I think we agree that the contraception section is not the strongest part of the post. On your specific point though, I don’t think it’s actually so bad to use the $9.4bn divided by 74 million.
You suspect that $9.4bn is calculated by looking at data from a much smaller sample and performing a simple extrapolation. So do I. But that’s actually exactly what we want—this advice is intended for people donating thousands, not billions. (This point is what I was trying to get at with my note about more-expensive “last-mile” contraceptive needs).
Good points all. Yours was a reasonable estimate, but the topic made it a good way to discuss certain general problems with this type of estimate, which are often more prominent in estimates made by other people in other situations.
(Also, I didn’t spot the “last mile” comment; sorry for missing that, and thanks for calling it to my attention.)
I agree on a meta level that the section on contraception shouldn’t be here.
On the object level, this isn’t the first time I’ve seen a charity analysis make the assumption that a problem can be completely solved if you multiply “cost to solve X% of the problem” by 100/X. This seems unlikely to be true in most cases, and is an important mistake to avoid.
For example, even if Guttmacher is correct that $9.4 billion will allow us to meet all unmet demand for contraceptives, contraceptives aren’t always used correctly, and even when used correctly, they don’t always work, so we won’t stop all 74 million unintended pregnancies. Also, not every unintended pregnancy leads to a child being born. And I suspect (from a brief skim of the report, I could be wrong here) that the $9.4 billion number involves some basic multiplication on Guttmacher’s part, without fully accounting for how difficult it is to reach different populations (in communities where contraceptives are forbidden, how much will it cost to change that policy?).
It’s still valuable to estimate and round, but the “multiply the number of people by the cost per person” fallacy (is there a catchier name?) seems like it routinely underestimates the cost of fully “fixing” a problem for reasons like these: Some % of your target population is hard to reach, and the thing that you think will always fix the problem only fixes it some % of the time.
Aaron, I think we agree that the contraception section is not the strongest part of the post. On your specific point though, I don’t think it’s actually so bad to use the $9.4bn divided by 74 million.
You suspect that $9.4bn is calculated by looking at data from a much smaller sample and performing a simple extrapolation. So do I. But that’s actually exactly what we want—this advice is intended for people donating thousands, not billions. (This point is what I was trying to get at with my note about more-expensive “last-mile” contraceptive needs).
Also remember I’m aiming for a rough estimate.
Good points all. Yours was a reasonable estimate, but the topic made it a good way to discuss certain general problems with this type of estimate, which are often more prominent in estimates made by other people in other situations.
(Also, I didn’t spot the “last mile” comment; sorry for missing that, and thanks for calling it to my attention.)