Hi Scott, thanks for your questions! Good questions, let me try some responses.
This is clearly the most difficult parameter to measure. We thought .5-10% represented a reasonable yet conservative range of potential values. I’d say “conventional wisdom” (ie what quite a number of the people we’ve spoken with have argued, but certainly not everyone agrees) is that you can draw a pretty straight line between the recent work of policy-focused climate activism groups like Sunrise and subsequent placement of climate as a high priority for the Biden administration. All of that being said, we agree that it’s relatively arbitrary. As we move forward to look at specific organizations, we’ll try to do a bit more work to get more reasonable values for these parameters. But it’s not clear how much better (if anything) we’ll be able to do.
We were trying to make this CEA a bit more general but it was clearly calibrated on Sunrise. I think you should interpret the model as representing a single, effective activism organization with a specific budget. So if we were trying to use the model to hone in on Sunrise’s impact, we’d say that for Sunrise’s budget of ~25 million over 5 years, we think this caused X% increase of a broad, progressive bill being passed. You could also extrapolate this to the movement in general, but then you’d use a larger budget and a larger % change.
We aren’t making that claim, but if you wanted to extrapolate this model to a future marginal increase in spending, then yes you’d need this assumption. I’d agree this is dodgy, but also I’m not sure the best way to extrapolate a total effect to marginal effect. Probably would just have to do some kind of discounting to account for diminishing marginal effects. This is something we should definitely think about, so thanks for bringing it up.