I’m not sure where you are disagreeing, because I agree that many people founding groups since 2015 will in fact have joined the movement later than 2015. Indeed, as I show in the first graph in the comment you’re replying to, newer cohorts of EA are much larger than previous cohorts, and as a result most people (>60%) in the movement (or at least the EA Survey sample[^1]) by 2019 are people who joined post-2015. Fwiw, this seems like more direct evidence of growth in EA since 2015 than any of the other metrics (although concern about attrition mean that it’s not straightforward evidence that the total size of the movement has been growing, merely that we’ve been recruiting many additional people since 2015).
My objection is that pointing to the continued growth in number of EA groups isn’t good evidence of continued growth in the movement since 2015 due to lagginess (groups being founded by people who joined the movement in years previous). It sounds like your objection is that since we also know that some of the groups are university groups (albeit a slight minority) and university groups are probably mostly founded by undergraduates, we know that at least some of the groups founded since 2015 were likely founded by people who got into EA after 2015. I agree this is true, but think we still shouldn’t point to the growth in number of new groups as a sign of growth in the movement because it’s a noisy proxy for growth in EA, picking up a lot of growth from previous years. (If we move to pointing to separate evidence that some of the people who founded EA groups probably got into EA only post 2015, then we may as well just point to the direct evidence that the majority of EAs got into EA post-2015!)
[^1]: I don’t take this caveat to undermine the point very much because, if anything I would expect the EA Survey sample to under-represent newer, less engaged EAs and over-represent EAs who have been involved longer.
I think maybe I was confused about what you are saying. You said:
I think this applies to growth in local groups particularly well… While I’ve no doubt that many of the groups that have been founded by people who joined since 2015*, I suspect that even if we cut those people out of the data, we’d still see an increase in the number of local groups over that time frame- so we can’t infer that EA is continuing to grow based on increase in local group numbers.
But then also:
Fwiw, this seems like more direct evidence of growth in EA since 2015 than any of the other metrics
In my mind, A being evidence of B means that you can (at least partially) infer B from A. But I’m guessing you mean “infer” to be something like “prove”, and I agree the evidence isn’t that strong.
DM: While I’ve no doubt that many of the groups that have been founded by people who joined since 2015*, I suspect that even if we cut those people out of the data, we’d still see an increase in the number of local groups over that time frame- so we can’t infer that EA is continuing to grow based on increase in local group numbers.
BW: It sounds like maybe when you say “we can’t infer that EA is continuing to grow based on increase in local group numbers” you mean “part of the growth might be explained by things other than what would be measured by a change in number of groups”? (Or possibly “increasing group numbers is evidence of growth since 2015, but not necessarily evidence of growth since, say, 2019”?)
I meant something closer to: ‘we can’t infer Y from X, because we’d still expect to observe X even if ¬Y.’
My impression is still that we have been somewhat talking past each other, in the way I described in the second paragraph of my previous comment. My core claim is that we should not look at the number of new EA groups as a proxy for growth in EA, since many new groups will just be a delayed result of earlier growth in EA, (as it happens I agree that EA has grown since 2015, but we’d see many new EA groups even if it hadn’t). Whereas, if I understand it, your claim seems to be that as we know that at least some of the new groups were founded by new people to EA, we know that there has been some new EA growth.
I’m not sure where you are disagreeing, because I agree that many people founding groups since 2015 will in fact have joined the movement later than 2015. Indeed, as I show in the first graph in the comment you’re replying to, newer cohorts of EA are much larger than previous cohorts, and as a result most people (>60%) in the movement (or at least the EA Survey sample[^1]) by 2019 are people who joined post-2015. Fwiw, this seems like more direct evidence of growth in EA since 2015 than any of the other metrics (although concern about attrition mean that it’s not straightforward evidence that the total size of the movement has been growing, merely that we’ve been recruiting many additional people since 2015).
My objection is that pointing to the continued growth in number of EA groups isn’t good evidence of continued growth in the movement since 2015 due to lagginess (groups being founded by people who joined the movement in years previous). It sounds like your objection is that since we also know that some of the groups are university groups (albeit a slight minority) and university groups are probably mostly founded by undergraduates, we know that at least some of the groups founded since 2015 were likely founded by people who got into EA after 2015. I agree this is true, but think we still shouldn’t point to the growth in number of new groups as a sign of growth in the movement because it’s a noisy proxy for growth in EA, picking up a lot of growth from previous years. (If we move to pointing to separate evidence that some of the people who founded EA groups probably got into EA only post 2015, then we may as well just point to the direct evidence that the majority of EAs got into EA post-2015!)
[^1]: I don’t take this caveat to undermine the point very much because, if anything I would expect the EA Survey sample to under-represent newer, less engaged EAs and over-represent EAs who have been involved longer.
I think maybe I was confused about what you are saying. You said:
But then also:
In my mind, A being evidence of B means that you can (at least partially) infer B from A. But I’m guessing you mean “infer” to be something like “prove”, and I agree the evidence isn’t that strong.
I meant something closer to: ‘we can’t infer Y from X, because we’d still expect to observe X even if ¬Y.’
My impression is still that we have been somewhat talking past each other, in the way I described in the second paragraph of my previous comment. My core claim is that we should not look at the number of new EA groups as a proxy for growth in EA, since many new groups will just be a delayed result of earlier growth in EA, (as it happens I agree that EA has grown since 2015, but we’d see many new EA groups even if it hadn’t). Whereas, if I understand it, your claim seems to be that as we know that at least some of the new groups were founded by new people to EA, we know that there has been some new EA growth.