> I'm pretty sure effective altruists have the same question, crunched the numbers, and figured out it was something like malaria nets or similar interventions in developing countries.
I wonder how much real world experience goes into these calculations. For instance the theory of malaria nets can be quite different from reality. From Wikipedia [1]:
> Where mosquito nets are freely or cheaply distributed, local residents sometimes opportunistically use them inappropriately, for example as fishing nets. When used for fishing, mosquito nets have harmful ecological consequences because the fine mesh of a mosquito net retains almost all fish, including bycatch such as immature or small fish and fish species that are not suitable for consumption. In addition, insecticides with which the mesh has been treated, such as permethrin, may be harmful to the fish and other aquatic fauna.