But as you mention, there are still other uncertainties, and discounting would be the easiest way to deal with those.
To avoid doing harder math, if we assume a 20 year lifespan and no discounting, we’d be at around $16 per DALY (instead of $10 per DALY).
Willie would probably have a better answer for you here and I think he’s going to take a look at this! My understanding is that there are only a couple parts of the well that are at much risk of needing maintenance, and those parts are replaced roughly every 10 years. But there isn’t an expectation that maintenance costs will increase over time
Good point! It looks like the U5 mortality rate in Niger has gone down ~ 10% in the past decade, so diarrhea morbidity also has probably improved. Maybe the easiest way to deal with this is through discounting? Or we can just assume the diarrhea burden goes down ~1% per year
Thanks. I can’t figure out what our source was for 20%, but changing to 18% wouldn’t make a big difference
No idea on this one! Hopefully Willie can talk a bit about that when he checks this out. 1,200 does seem high when I look up “how many people share a water well in africa?”
Thanks for sharing this! We hadn’t seen your post but its very interesting!
We agree the cross-sectional studies we cited are super limited, which is why we relied on GiveWell’s chlorination mortality estimates in our initial draft.
We moved away from GiveWell’s numbers after we got a comment suggesting wells are a bit less effective than chlorination, because water can get contaminated between when its taken from the well and when its used.
We should probably just use GiveWell’s numbers and apply a small penalty for wells (can’t imagine wells are more than 10-15% less effective?). That way we aren’t relying on these meh papers, and can instead rely on a team that’s spent a lot of time thinking about this.
We get very similar estimates when we use GiveWell’s numbers, so I don’t think this would change much. Though if you’re right that GiveWell might be underestimating the effect, that would obviously improve things.
My guess is that making some of the changes mentioned above might 2x-3x the cost per DALY, to something like $20-$30, which would still be great!
Nice one love it, all sounds very reasonable. With CEAs there are always so many tricky decisions to make. Keep in mind this isn’t my specific area of expertise so don’t over index on my suggestions too much 😊.
I’m not sure why there hasn’t been more high quality research on wells given how common an intervention it is. The one big RCT in Ghana i could find showed a reduction in diarrhea if stuff 15 percent, similar to other water cleaning interventions.
Thanks for such a thoughtful reply Nick!
Fair points. We think the 50 year expected lifespan is reasonable, but we should probably account for uncertainty.
Water-wise, it sounds like the basin under Niger is much larger than in other parts of Africa, so there isn’t a risk of the water running out soon.
But as you mention, there are still other uncertainties, and discounting would be the easiest way to deal with those.
To avoid doing harder math, if we assume a 20 year lifespan and no discounting, we’d be at around $16 per DALY (instead of $10 per DALY).
Willie would probably have a better answer for you here and I think he’s going to take a look at this! My understanding is that there are only a couple parts of the well that are at much risk of needing maintenance, and those parts are replaced roughly every 10 years. But there isn’t an expectation that maintenance costs will increase over time
Good point! It looks like the U5 mortality rate in Niger has gone down ~ 10% in the past decade, so diarrhea morbidity also has probably improved. Maybe the easiest way to deal with this is through discounting? Or we can just assume the diarrhea burden goes down ~1% per year
Thanks. I can’t figure out what our source was for 20%, but changing to 18% wouldn’t make a big difference
No idea on this one! Hopefully Willie can talk a bit about that when he checks this out. 1,200 does seem high when I look up “how many people share a water well in africa?”
Thanks for sharing this! We hadn’t seen your post but its very interesting!
We agree the cross-sectional studies we cited are super limited, which is why we relied on GiveWell’s chlorination mortality estimates in our initial draft.
We moved away from GiveWell’s numbers after we got a comment suggesting wells are a bit less effective than chlorination, because water can get contaminated between when its taken from the well and when its used.
We should probably just use GiveWell’s numbers and apply a small penalty for wells (can’t imagine wells are more than 10-15% less effective?). That way we aren’t relying on these meh papers, and can instead rely on a team that’s spent a lot of time thinking about this.
We get very similar estimates when we use GiveWell’s numbers, so I don’t think this would change much. Though if you’re right that GiveWell might be underestimating the effect, that would obviously improve things.
My guess is that making some of the changes mentioned above might 2x-3x the cost per DALY, to something like $20-$30, which would still be great!
Nice one love it, all sounds very reasonable. With CEAs there are always so many tricky decisions to make. Keep in mind this isn’t my specific area of expertise so don’t over index on my suggestions too much 😊.
I’m not sure why there hasn’t been more high quality research on wells given how common an intervention it is. The one big RCT in Ghana i could find showed a reduction in diarrhea if stuff 15 percent, similar to other water cleaning interventions.
tohttps://pmc.ncbi.nlm.nih.gov/articles/PMC4626959/