The last Open Thread was in October 2017, so I thought we were overdue for a new one.
Use this thread to post things that are awesome, but not awesome enough to be full posts. This is also a great place to post if you don't have enough karma to post on the main forum.
Consider giving your post a brief title to improve readability.
Another way of saying it is “Sometimes pulling numbers out of your arse and using them to make a decision is better than pulling a decision out of your arse.” It's taken from http://slatestarcodex.com/2013/05/02/if-its-worth-doing-its-worth-doing-with-made-up-statistics/ which is relevant here.
Sure, but I don't think those are the only options.
Possible alternative option: come up with a granular theory of change; use that theory to inform decision-making.
I think this is basically what MIRI does. As far as I know, MIRI didn't use cost-effectiveness analysis to decide on its research agenda (apart from very zoomed-out astronomical waste considerations).
Instead, it used a chain of theoretical reasoning to arrive at the intervention it's focusing on.