Thanks John!

Which kinds of qualitative analysis do you think are important, and why? Is that what you're talking about when you later write this ...

Yes. See also the first section of my response to wdcrouch.

Did you spend time looking for ways in which projects could be more effective than initially expected, or only ways in which they could be less effective?

• Empirically, best guess cost-effectiveness estimates as measured in lives directly saved have consistently moved in the direction of worse cost-effectiveness. So taking the outside view, one would expect more such updates. Thus, one should expect the factors that could give rise to less cost-effectiveness as measured lives directly saved to outweigh the factors that could give rise to more cost-effectiveness as measured in lives directly saved.

• I didn't make a concerted effort to look for ways in which the cost-effectiveness as measured in lives directly saved could be better rather than worse. But I also don't know of any compelling hypotheticals. I would welcome any suggestions here.

For example: did you think much about the 'multiplier effects' where making someone healthier made them better able to earn a living, support their relatives, and help other people... thus making other people healthier as well?

I agree that these could be very significant. See the second section of my response to wdcrouch's comment.