And so, knowing that the true cumulative impact of a donation is never certain, why did I still choose to donate?

Why did you phrase it like this—what does being certain about the cumulative impact have to do with the choice of whether to donate or not? Why isn’t the expected impact more important?

This is a serious question, I have the same psychological issue where certainty of a positive outcome is sometimes more important than positive expected value. But I don’t yet have a rule which allows me to predict when this psychological effect will come into play.

oooh, don’t get me started on expectation values… I have heated opinions here, sorry. The two easiest problems with expectations in this case is that to average something, you need to average over some known space, according to some chosen measure—neither of which will be by any means obvious in a real-world scenario. More subtly, with real-world distributions, expectation values can often be infinite or undefined, and median might be more representative—but then should you look at mean, median, or what else?

Why did you phrase it like this—what does being certain about the cumulative impact have to do with the choice of whether to donate or not? Why isn’t the expected impact more important?

This is a serious question, I have the same psychological issue where certainty of a positive outcome is sometimes more important than positive expected value. But I don’t yet have a rule which allows me to predict when this psychological effect will come into play.

oooh, don’t get me started on expectation values… I have heated opinions here, sorry. The two easiest problems with expectations in this case is that to average something, you need to average over some known space, according to some chosen measure—neither of which will be by any means obvious in a real-world scenario. More subtly, with real-world distributions, expectation values can often be infinite or undefined, and median might be more representative—but then should you look at mean, median, or what else?