Very nice article!

I too wonder exactly what you mean by

effective altruists should spend much more time on qualitative analysis than on quantitative analysis in determining how they can maximize their positive social impact.

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

Estimating the cost-effectiveness of health interventions in the developing world has proved to be exceedingly difficult, and this in favor of giving more weight to inputs for which it’s possible to make relatively well-grounded assessments. Some of these are room for more funding, the quality of the people behind a project and historical precedent.

?

I also have a question. 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. 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?

Even if your only ultimate concern were saving lives - which seems narrow-minded to me, and also a bit vague since all these people eventually die - it seems effects like this tend to turn other good things into extra lives saved.

It could be very hard to quantify these multiplier effects. But just as you'll find many negative feedbacks if you look hard for them, like these:

• Fathers may steal nets from pregnant mothers and sell them for a profit.

• LLIN recipients may use the nets for fishing.

• LLIN users may not fasten LLINs properly.

• Mosquitoes may develop biological resistance to the insecticide used on LLINs.

there could also be many positive feedbacks you'd find if you'd looked for those. So I'm a bit concerned that you're listing lots of "low-probability failure modes" but no "low-probability better-success-than-expected modes".