Carl’s comment renders this irrelevant for CEA lotteries, but I think this reasoning is wrong even for the type of lotteries you imagine.
In either one the returns are good in expectation purely based on you getting a 20% chance to 5x your donation (which is good if you think there’s increasing marginal returns to money at this level), but also in the other 80% of worlds you have a preference for your money being allocated by people who are more thoughtful.
What you’re forgetting is that in the 20 % of worlds where you get your donation, you’d rather have been in the pool without thoughtful people. If you were, you will get to regrant 50k smartly, and a thoughtful person will get to regrant 40k. However, if you were in the pool with thoughtful people, the thoughtful people won’t get to regrant any money, and the 40k in the thoughtless group will go to some thoughtless cause.
When joining a group (under your assumptions, that aren’t true for CEA), you increase the winnings of everyone while decreasing the probability that they win. In expectation, they all get to regrant the same amount of money. So the only situation where the decision between groups matter is if you have some very specific ideas about marginal utility, e.g. if you want to ensure that there exists at least one thoughtful lottery winner, and don’t care much about the second.
But insofar as the lottery enhances the effectiveness of donors (by letting them invest more in research if they win, amortized against a larger donation), then you want donors doing good to be enhanced and donors doing bad not to be enhanced. So you might want to try to avoid boosting pot size available to bad donors, and ensure good donors have large pots available. The CEA lottery is structured so that question doesn’t arise.
There is also the minor issue of correlation with other donors in the same block mentioned in the above comment, although you could ask CEA for a separate block if some unusual situation meant your donation plans would change a lot if you found out another block participant had won.
Carl’s comment renders this irrelevant for CEA lotteries, but I think this reasoning is wrong even for the type of lotteries you imagine.
What you’re forgetting is that in the 20 % of worlds where you get your donation, you’d rather have been in the pool without thoughtful people. If you were, you will get to regrant 50k smartly, and a thoughtful person will get to regrant 40k. However, if you were in the pool with thoughtful people, the thoughtful people won’t get to regrant any money, and the 40k in the thoughtless group will go to some thoughtless cause.
When joining a group (under your assumptions, that aren’t true for CEA), you increase the winnings of everyone while decreasing the probability that they win. In expectation, they all get to regrant the same amount of money. So the only situation where the decision between groups matter is if you have some very specific ideas about marginal utility, e.g. if you want to ensure that there exists at least one thoughtful lottery winner, and don’t care much about the second.
Yes, the main effect balances out like that.
But insofar as the lottery enhances the effectiveness of donors (by letting them invest more in research if they win, amortized against a larger donation), then you want donors doing good to be enhanced and donors doing bad not to be enhanced. So you might want to try to avoid boosting pot size available to bad donors, and ensure good donors have large pots available. The CEA lottery is structured so that question doesn’t arise.
There is also the minor issue of correlation with other donors in the same block mentioned in the above comment, although you could ask CEA for a separate block if some unusual situation meant your donation plans would change a lot if you found out another block participant had won.