Please correct me if I'm being silly, but I was looking to evaluate animal advocacy against corporate campaigns and came up with an estimate far lower than Open Philanthropy's one (at least 2 orders of magnitude lower).
I then reviewed their work and found a very odd set of logic. Open Phil claims
At any time, about 265 million U.S. egg-laying hens are confined in microwave oven-sized cages
But then later claims:
Counting just the ~$2.5 million spent on corporate cage-free campaigning over the last few years, and conservatively assuming that the campaigns only accelerated pledges by five years, these campaigns will spare about 250 hens a year of cage confinement per dollar spent.
That seems to imply that the intervention would save hens. But that's 2 and a half times the number of hens even in confinement! Have I made an error? What assumptions am I missing?
Ahh, that makes sense. I think "250 Hens a year" sounds like "250 Hens/year" not "250 hens * year". That's probably where I got my mistake
I would go so far as to say your interpretation is correct and the original text is wrong, it should read "hen-years", not "hens a year".