TL;DR: As you begin community building in the EA space, it can be unclear how many enaged members you can expect to produce, in this post I estimate that only 0.0026% of the population of people who have "been outreached to" become active EAs, for most university groups this implies about 1-2 active EAs across your whole population. This is an underestimate (reasons detailed below), as such I encourage you to see this as as an absolute lower bound (and attainable target) for production of level 3-5 engaged Effective Altruists.
Introduction
Below is a quick take on the number of members taking significant action that you can expect to have in your university group. This is based on proportions of engagement with EA following outreach and makes lots of assumptions. Where I am aware of them I have tried to highlight these assumptions and indicate the extent to which they imply the figure is an over or underestimate.
Simply, I first estimate the number of people who have heard of EA (engaged with the ideas), I then estimate the number of people taking significant action, Express this as a proportion and multiply it by the population of my university (Durham), this provides an estimated upper bound for the number of people taking significant action in my university.
# of people that have heard of EA
Using the inclusive stringent definition of having heard of EA figures from this report by Rethink Priorities. Which is still believed to be an overestimate by RP, 2.6% of the US adult population has heard of EA. (based on answers to definition based questions, rather than self-reporting qualitative judgements of levels of engagement. In particular by selecting for answers one would be very unlikely to be able to give they had not actually encountered effective altruism))
This is still taken to be an overestimate because people can guess at a passable definition of EA by simply knowing the meanings of the words Effective and Altruism - evidenced by many surveyors self-reporting no prior knowledge of EA but still meeting stringent criteria in later answers.
Extending this 2.6% globally is also a significant overestimate for many reasons, such as: There is correlation between Higher levels of education and engagement with EA; Proximity bias (San Fran hub etc.). Instead estimate US, Canada and Europe number with this figure and apply a 30% discount rate to ROW. (this is an inutitive guess based on proportion of highly educated populations and the concentration of EA groups)
Global Population = ~8.2 billion
US population = ~340.1 million
Canada population = ~ 41.9 million
EU population = ~744.3 million
Rest of World population = ~7.07 billion
Therefore the number of people who have heard of EA in a stringent manner can be roughly 29,283,000 ((340.1+41.9+744.3)million *0.026) for the US, Canada and Europe and 128,674,000 (7.07 billion*2.6%*0.7) for the Rest of the world. This gives a total outreached population of 157,957,000.
How many Engaged EAs are there?
Method 1: Rethink Priorities and 80k Study extrapolated
In 2019 there were an estimated 6500 active EAs at the level 3-5 level (moderately engaged and above), In the 80k post about community building and allocation of resources, Rob estimates a 14% growth rate for 2020. I will assume this growth rate remains consistent (I have no reason to update or believe my estimate will be better, and I am unable to evaluate any changes in CEA strategy since 2020). This means that as of today we have = 11986 (4 and two thirds years since 2020, this is important because I'm using current population)
Method 2: Forum Members
To estimate the number of people that respond to the EA survey I have sent polls into my GCP group chat and in the UK G.O.R. asking whether they responded.
The 2024 survey had 1916 respondents. (There is no 2025 survey, I will assume a 14% growth rate). Approx 60% of the small people I surveyed who are active EAs said that they filled in the survey. if 1916 represents 60% of active EAs, then there are 1916/0.6 = 4786 active EAs in 2024.
This is an underestimate for two significant reasons, the first being that EA community builders love surveys and the majority of people I asked were community builders and so are more likely than "the average EA" to respond to a survey. The second that responses to this poll were public so there is some social embarrassment that comes with answering no, so people are much more likely to answer yes. These together imply to me that I should estimate the percentage of respondents 40% higher than above.
Applying this internal validity discount as well as the 14% growth rate we estimate 4786*1.4*1.14=7638
This survey reached very few people so we can have only low credence in assuming this represents an accurate response rate to the survey.
Weighted Average Number of active EAs
We can have only low credence in method 2, the sample was very small and a large validity discount is a good proxy for huge uncertainty, I will therefore trust Rob (& the 80k team) and weight the methods 70% to 30% leaving a weighted average estimate for the number of active EAs as 70%*11986+30%*7638 = 10,682.
Conclusions
Proportion of people that, when outreached to, become an Active EA is therefore roughly 10,682/157,957,000 = 0.0068%
For my university student population of 20,000, this means that if we successfully managed to outreach to every single member, we could expect 20,000*0.000068 = 1.35 active EAs.
There are several noteworthy reasons this is a significant underestimate and I think it is useful to think about them:
- This assumes a completely equal distribution in quality of outreach globally - this is of course wrong. People are better or worse at outreach and in general group organisers receive training and guidance on effective outreach, this will non-trivially increase the proportion of engagement with the EA principles and community
- This treats all people as having similar capacity to commit time, money or other resources to Effective Altruism, university groups are necessarily engaging (in general) wit students that have more of these resources, so will have higher uptake (at least during their time at university).
Some less of note reasons I think this figure might represent an underestimate is that 2.6% is too high even for the US, Rethink mention false positives. And my discount rate is likely too low based on the spread of EAs globally but I didn't want to model the proportion of outreached EAs based on the # of active EAs in those locations as this seems circular!
p.s. Hopefully this can serve as motivation to university organisers - you're doing okay! :)
Thanks Arthur for sharing your work on this, and backing it up with relevant numbers and data. Internally, we’ve used an app I developed to help try to get a handle on how levels of awareness in the population might translate to engaged members of the community and vice versa - you can take a look and see if it is in any way helpful in working with some of the numbers/estimates you make in this post.
It might also interest you to know that we have a more recent, more detailed and, we think, more accurate estimate of the number of people who’ve heard of EA in the US, which you can find here (though the app I’ve linked still uses the older numbers you’re referring to, as we made it around the same time that report was released).
I think your overall assessment is right that we shouldn’t expect a massive conversion rate for people merely hearing of EA to becoming highly engaged members of the EA community, and this can temper possible feelings of inadequacy among community builders. That being said, it’s important not to conflate ‘hearing of EA’ with ‘EA outreach’, and also to keep in mind the individual and social context in which outreach or hearing of EA is taking place.
While the percentage of the population who’ve potentially heard of EA is already rather low, the percentage who’ve been ‘reached out to’ is going to be lower still. Demographic features associated with liking EA are higher amongst university students than the general population. In addition, something like a ‘stages of change’ model likely applies, in which many people attending university may be actively seeking something to dedicate themselves to, or at least actively seeking group or club membership, and are therefore more responsive than gen pop. Finally, the sort of exposure to EA that might occur as a result of a university group outreach/presence on campus and fairs is likely very different and more active than potentially passive exposure that might occur more broadly. These things come together to make university outreach quite different from a random member of the population just coming across EA and deciding to get involved.
I mention these things because even considering - as you rightly do - the ability of those doing the outreach or people at university having more time or resources, the starting conversion rate of .0068% might plausibly make university outreach seem somewhat hopeless or useless - I’d think you can substantially beat those odds derived just from the gen pop!
[the screenshot is just an example of some of the kinds of output from the app, not substantively anything to consider in terms of the numbers]
Agreed with Jamie's points above.
A couple of additional points:
We'd be happy to repeat either of these surveys if people are interested.
The results are directionally similar if you exclude those who "Don't remember", which is much more common for the general population.
Thank you both for your replies!
Jamie you're completely right that "Reached out to" was a lazy definition. I mention briefly the inequality of distribution for the quality of outreach but this assumes outreach - completely ignoring passive routes to hearing about EA, which of course will have lower take-up rates. This should be clear, and would massively increase estimates of the conversion rate for outreach. Thank you :)
However, a university group cannot "perform outreach" to their entire university, so - hopefully to a lesser extent than with gen pop due - lots of their student population who hear about EA will necessarily only hear about it passively (through flyers or mailing lists) right? (remember I'm trying to estimate take-up based on entire university student populations)
It seems David's comment below is particularly relevant here, and that it might be useful to have a two-way table of uptake rates? With University/General population on one axis and Passive/Active on the other. (Let me know if this exists and I'm missing it, otherwise if you agree this might be useful I can try and use any relevant surveys to estimate this)
This will work to motivate community builders with clear evidence of their better position with respect to uptake than a gen pop community builder. As well as presumably (based on the findings shared by David) active outreach (speaking to people etc.) over passive methods even within university outreach. Also comparing passive take-up in gen pop and University populations will also provide empirical support for the "stages of change" model too right?
Thank you again!
Hi Arthur - just to be clear I wouldn't call any part of your post 'lazy'!
Certainly a university group wouldn't be actively speaking to every person on campus. We may just need to be very precise about what we mean, and perhaps even a single dimension of active vs. passive might not cut it. For example I'd say that flyering or mailing lists are more active forms of outreach/exposure than the type of exposure I'm imagining often happens in the general population (like just seeing a news article that mentions EA, possibly disparagingly), and they also offer a route to participation for those interested. Some other dimensions would likely be whether the context of the exposure presents EA as positive or negative, and whether it is coming from the EA community or simply something about EA.
We don't have a direct assessment of 'uptake rates' although maybe, at least for the US, we could look at making something that at least sheds some light on it (e.g., looking at % hearing of EA in US adult demographics, vs. US respondent demographic % in the EA survey - though I think you are right that the EA survey definitely does not capture everyone and we don't strictly know the composition of the 'EA community', unfortunately, which may limit the value of doing this). Of possible interest is that we observed in the most recent Pulse results that 'elite' universities in the US (~top 20 ranked) had higher awareness of EA than other universities. David may have more insight into other findings/data from the EA survey that would be of relevance in terms of outreach/exposure types.
Thanks Arthur! Unfortunately, I'm not sure that this data exists. It seems that we'd need to know both how many EA members there are at different universities and where they first heard of EA (perhaps CEA could gather this in future groups surveys).
We do have data about where people on campus in general had heard of EA.[1] Interestingly, ~0 of the people in our sample who seemed to have encountered EA (~220 people) seemed to be EAs themselves, which is itself somewhat suggestive of conversion rates.
As we can see, people on campus are more likely to say they heard of EA due to an EA group (14%), or a club fair (7%), that is probably likewise attributable to direct group activity. Some of the people who simply heard about EA around campus or from friends may also be attributable to group activity, but not have been directly outreached to. Many people clearly encountered EA only through more indirect means though, e.g. wider media, school or classes.[2]
This excludes responses which did not give an interpretable answer as to where they had heard of EA.
Though it is worth bearing in mind that what we count as direct/indirect or higher/lower quality outreach is somewhat theoretically laden (and these dimensions can come apart). I recall, many years ago, it was more common to believe that people reading books would be 'high fidelity', and that groups might be 'lower fidelity'; now a minority view.