(1) Theoretically, additional detail to your CEA means: (a) a more discrete and granular theory of change, which necessarily reduces the probability of success, and (b) trying to measure more flow-through effects/externalities, which while typically positive, are more uncertain and tend also to be less important compared to the primary health effects measured. With the impact of (a) > (b), more research attrites the estimated cost-effectiveness.
(2) Empirically, and from past experience, this has been the case for various organizations, to my understand. Eric Hausen has spoken about Charity Science Health’s process (more you look at something, the worse it seems), and GiveWell has written about this before, I believe (somewhere, might dig it up eventually!)
(1) Theoretically, additional detail to your CEA means: (a) a more discrete and granular theory of change, which necessarily reduces the probability of success, and (b) trying to measure more flow-through effects/externalities, which while typically positive, are more uncertain and tend also to be less important compared to the primary health effects measured. With the impact of (a) > (b), more research attrites the estimated cost-effectiveness.
(2) Empirically, and from past experience, this has been the case for various organizations, to my understand. Eric Hausen has spoken about Charity Science Health’s process (more you look at something, the worse it seems), and GiveWell has written about this before, I believe (somewhere, might dig it up eventually!)