I think this applies to growth in local groups particularly well. As I argued in this comment above, local groups seem like a particularly laggy metric due to people usually starting local groups after at least a couple of years in EA. 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.
*Indeed, we should expect this because most people currently in the EA community (at least as measured by the EA Survey) are people who joined since 2015. In each EA survey, the most recent cohorts are almost always much larger than earlier cohorts (with the exception of the most recent cohort of each survey since these are run before some EAs from that year will have had a chance to join). See this graph which I previously shared, from 2019 data, for example:
(Of course, this offers, at best, an upper bound on growth in the EA movement, since earlier cohorts will likely have had more attrition).
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do you think it’s likely that there are about as many group members as before, spread across more groups? Or maybe there are more group members, but the same number of total people engaged in EA, with a higher % of people in groups than before?
There’s definitely been a very dramatic increase in the percentage of EAs who are involved in local groups (at least within the EA Survey sample) since 2015 (the earliest year we have data for).
In EAS 2019 this was even higher (~43%) and in EAS 2020 it was higher still (almost 50%).
So higher numbers of local group members could be explained by increasing levels of engagement (group membership) among existing EAs. (One might worry, of course, that the increase in percentage is due to selective attrition, but the absolute numbers are higher than 2015 as well.)
Unfortunately we don’t have good data on the number of local group members, because the measures in the Groups Survey were changed between 2019-2020. On the one measure which I was able to keep the same (total number of people engaged by groups) there was a large decline 2019-2020, but this is probably pandemic-related.
University group members are mostly undergraduates, meaning they are younger than ~22. This implies that they would have been younger than 18 in 2017, and there was almost no one like that on the 2017 survey. And they would have been under 16 in 2015, although I don’t think we have data going back that far. I can think of one or two people who might have gotten involved as 15-year-olds in 2015, but it seems quite rare. Is there something I’m missing?
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 think this applies to growth in local groups particularly well. As I argued in this comment above, local groups seem like a particularly laggy metric due to people usually starting local groups after at least a couple of years in EA. 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.
*Indeed, we should expect this because most people currently in the EA community (at least as measured by the EA Survey) are people who joined since 2015. In each EA survey, the most recent cohorts are almost always much larger than earlier cohorts (with the exception of the most recent cohort of each survey since these are run before some EAs from that year will have had a chance to join). See this graph which I previously shared, from 2019 data, for example:
(Of course, this offers, at best, an upper bound on growth in the EA movement, since earlier cohorts will likely have had more attrition).
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There’s definitely been a very dramatic increase in the percentage of EAs who are involved in local groups (at least within the EA Survey sample) since 2015 (the earliest year we have data for).
In EAS 2019 this was even higher (~43%) and in EAS 2020 it was higher still (almost 50%).
So higher numbers of local group members could be explained by increasing levels of engagement (group membership) among existing EAs. (One might worry, of course, that the increase in percentage is due to selective attrition, but the absolute numbers are higher than 2015 as well.)
Unfortunately we don’t have good data on the number of local group members, because the measures in the Groups Survey were changed between 2019-2020. On the one measure which I was able to keep the same (total number of people engaged by groups) there was a large decline 2019-2020, but this is probably pandemic-related.
University group members are mostly undergraduates, meaning they are younger than ~22. This implies that they would have been younger than 18 in 2017, and there was almost no one like that on the 2017 survey. And they would have been under 16 in 2015, although I don’t think we have data going back that far. I can think of one or two people who might have gotten involved as 15-year-olds in 2015, but it seems quite rare. Is there something I’m missing?
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.