GWWC’s 2023–2024 impact evaluation (executive summary)

By Aidan Whitfield🔸, Giving What We Can🔸 @ 2025-06-03T22:05 (+121)

This post presents the executive summary from Giving What We Can’s impact evaluation for the 2023–2024 period. At the end of this post we share links to more information, including the full report and working sheet for this evaluation. We look forward to your questions and comments!

This report estimates Giving What We Can’s (GWWC’s) impact over the 2023–2024 period, expressed in terms of our giving multiplier — the donations GWWC caused to go to highly effective charities per dollar we spent. We also estimate various inputs and related metrics, including the lifetime donations of an average 🔸10% pledger, and the current value attributable to GWWC and its partners for an average 🔸10% Pledge and 🔹Trial Pledge. 

Our best-guess estimate of GWWC’s giving multiplier for 2023–2024 was 6x, implying that for the average $1 we spent on our operations, we caused $6 of value to go to highly effective charities or funds. 

While this is arguably a strong multiplier, readers may wonder why this figure is substantially lower than the giving multiplier estimate in our 2020–2022 evaluation, which was 30x. In short, this mostly reflects slower pledge growth (~40% lower in annualised terms) and increased costs (~2.5x higher in annualised terms) in the 2023–2024 period. The increased costs — and the associated reduction in our giving multiplier — were partly due to one-off costs related to GWWC’s spin-out. They also reflect deliberate investments in growth and the diminishing marginal returns of this spending. We believe the slower pledge growth partly reflects slower growth in the broader effective altruism movement during this period, and in part that GWWC has only started shifting its strategy towards a focus on pledge growth since early 2024. We’ve started seeing some of this pay off in 2024 with about 900 new 🔸10% Pledges compared to about 600 in 2023. 

All in all, as we ramp up our new strategy and our investments start to pay off, we aim and expect to sustain a strong (at least 5x) average and marginal giving multiplier over the coming years, while significantly increasing our pledge growth and overall impact. This reflects that our ultimate goal is not to maximise our multiplier on a small budget, but instead to maximise our impact while spending our operational funds cost-effectively, strategically scaling our impact. Our long-term goal is to reach 1 million pledgers giving $3 billion annually to high-impact charities.

In this evaluation, we also revisited our estimate of the value of an average 🔸10% Pledge. In contrast to our 2020–2022 impact evaluation — which found that the average 🔸10% pledger’s donations remained stable or increased over time, in this evaluation, using new data and a different analytical approach, we now find that average pledge donations fall over time. This is mostly because, over time, the proportion of pledgers who continue to record significant donations falls while the average donations of pledgers who continue donating remain stable. This has caused us to update our estimates of pledge value: 

Our updated best-guess estimate is that the average 🔸10% pledger donates $100K USD[1] over the course of their pledge (between signing their pledge and retiring). 

After applying various discounts — for time (future donations may be less valuable than present ones), effectiveness (not all donations go to high-impact charities), and counterfactuality (some donations would have occurred without GWWC) — our best guess is that, for each 🔸10% Pledge, GWWC generates, on average, roughly $15K in counterfactual donations for high-impact charities — meaning these donations would not have happened without GWWC.[2] We emphasise that the changes since 2020–2022 reflect changes in our methodology and available data and not an expectation that pledges acquired in this period produced less value than in 2020–2022. These estimates remain uncertain, and we expect them to change over time — potentially in either direction.

The majority of our impact (roughly 75%) continues to come from our pledge work, with a minority coming from non-pledge donations made through our platform. We also find that the vast majority (>90%) of our pledge impact comes from 🔸10% Pledges, with a minority coming from 🔹Trial Pledges. These results validate the strategic reorientation towards 🔸10% Pledge growth that was informed by our 2020–2022 impact evaluation. They also identify significant room to improve ‘pledge quality’ — that is, the average value generated by a 🔸10% Pledge. In particular, we believe that we should consider focusing more efforts on combatting pledger attrition, as our results show only about 30% of 🔸10% pledgers are recording donations via our platform 5 years after commencing their pledge. This doesn’t necessarily mean these pledgers aren’t fulfilling their pledge — reporting is not a requirement, though it is strongly encouraged. That said, our most recent surveys of pledgers who don’t record their donations didn’t find a meaningful signal that most of these pledgers are, in fact, donating. Thus, these results show a strong case for addressing pledger attrition, an insight that we expect will inform our strategic plans going forward.

Finally, we emphasise that our results are sensitive to the specific approach we used to generate them, which is subject to many assumptions. We recommend that readers interested in learning more about the results read the ‘How to interpret our estimates’ section. Readers interested in specific calculations can refer to the relevant sections of the main report.

Where you can learn more

  1. ^

     All monetary figures provided here are adjusted for inflation to 2024 USD. 

  2. ^

    To avoid double-counting impact, our guidance for 2025 is that, for each new pledge, GWWC and our pledge partners attribute themselves $10K per🔸10% Pledge for their work that causes the pledge and GWWC should attribute $5K (over the lifetime of the pledge) for ongoing ‘pledge stewardship’ work.

Vasco Grilo🔸 @ 2025-06-05T13:57 (+13)

Thanks for sharing, Aidan! Great work.

The Centre for Exploratory Altruism Research (CEARCH) estimated GWWC's marginal multiplier to be 17.6 % (= 2.18*10^6/(12.4*10^6)) of GWWC's multiplier. This suggests GWWC's marginal multiplier from 2023 to 2024 was 1.06 (= 0.176*6), such that donating to GWWC over that period was roughly as cost-effective as to GiveWell's top charities. A marginal multiplier of 1 may look bad, but is actually optimal in the sense GWWC should spend more for a marginal multiplier above 1, and less for one below 1.

You estimate the mean annual donations across 10 % Pledgers by year of pledge, and use this to estimate the value of future pledges. Have you considered controlling not only for the year of the pledge, but also for the year in which the pledge started? I guess pledges starting in later years are less valuable, such that you are overestimating your impact by not controlling for the year the pledge started. To do this, I would:

I would be happy to run the regression above if you shared the recorded donations by pledger and year, and the years in which each pledge started. I am also open to making or reviewing other quantitative analyses related to GWWC's work for free.

Have you considered retiring The Trial Pledge? You estimated 96 % of your impact came from The 10 % Pledge.

Which fraction of the people who started The 10 % Pledge until the end of 2024 recorded a donation in 2024? I assume significantly less than 59.4 %, which is your estimate for the fraction of 10 % Pledgers recording a donation in the 1st year of their pledge. So I think the information below on GWWC's website is somewhat misleading. Maybe only around 1/3 (less than 59.4 %) of the members recorded a donation in 2024. In addition, you estimate only 12.3 % (= 1 - 1/1.14) of your impact from 2023 to 2024 came donations which were not recorded.

Our community includes 9,840 lifetime members pledging ≥10% of their income, plus 1,117 trial pledgers, together making up our 10,957 strong giving community

I had expressed my concerns about the above to GWWC 14 months ago. I sent the email below to @Michael Townsend🔸 (former researcher of GWWC) and @Sjir Hoeijmakers🔸 (former director of research, and current CEO of GWWC) with @GraceAdams🔸 (former and current director of marketing of GWWC) and @Luke Freeman 🔸 (former CEO of GWWC) in CC on 11 April 2024. Grace, Michael, and @Alana HF (current and former research communicator at GWWC) replied to my email.

Hi Michael and Sjir,

I was surprised to note 35.2 % of GWWC pledgers (including the 2 types of pledgers) have not reported any donation until 22 February 2023 (the date referring to the data I used in this analysis). Had you realised this? I thought the fraction could decrease substantially if I excluded recent pledgers, who may not have their reported donations up to date, but this barely affected the fraction. 34.4 % of GWWC pledgers who started their pledge before 2022 have not reported any donation.

It is possible the 1/3 of pledgers who have not reported any donation are still making significant donations. However, I have the impression it is not super clear from GWWC's comms and website that only around 2/3 of pledgers have reported more than 0 $ of donations (and around 44 % have reported less than 100 $/year). So I think it is worth clarifying that somehow, and may say something about it in the mistakes page. I guess it would be good to highlight in the website and comms the number of pledgers for which there is decent evidence that the pledge is being accomplished, which I assume could be operationalised as having enough reported donations relative to the reported income. Even then, it would be worth rechecking recurrent donations, which have been a problem in the past (for large donors).

I would normally draft an EA Forum post about the above, and then share it with you a few weeks before posting so that you could give feedback, and prepare a reply, but I guess it would be better for you to clear up the matter, and for me not to post anything. This is assuming that, conditional on my numbers being right, you think there is any problem in the comms or website as is. If my numbers are right, and you think the comms and website are still fine, then I would still be interested in drafting a post.

As a reality check of my numbers, I went back to the Lorentz curve I estimated for the value generated by each pledge. I have it in my post:

image.png
I did not notice it back then, but it is indeed the case that around 40 % of pledgers generate basically 0 value, which is consistent with the numbers I mentioned above. However, both are coming from the same source, so there is a decent chance of any error in one place also being present in the other.

I feel like this email is a bit too negative. Thanks for your great work!

Vasco

Aidan Whitfield🔸 @ 2025-06-13T11:13 (+13)

Hi Vasco, thanks for your engagement! I have put together some responses to your questions/comments below. Please let me know if I missed anything or you have further questions.

> The Centre for Exploratory Altruism Research (CEARCH) estimated GWWC's marginal multiplier to be 17.6 % (= 2.18*10^6/(12.4*10^6)) of GWWC's multiplier. This suggests GWWC's marginal multiplier from 2023 to 2024 was 1.06 (= 0.176*6), such that donating to GWWC over that period was roughly as cost-effective as to GiveWell's top charities. A marginal multiplier of 1 may look bad, but is actually optimal in the sense GWWC should spend more (less) for a marginal multiplier above (below) 1.

I would actually expect our marginal multiplier to be much closer to our average multiplier than the CEARCH method implies. Most importantly, I expect most of our marginal resources are dedicated to identifying and executing on scalable pledge growth strategies. I think this work, in expectation, provides a pretty strong multiplier. By comparison our average multiplier includes some major fixed costs (e.g., related to running our donation platform). 

It's also worth noting that pledge growth accelerated between 2023 and 2024, such that our average multiplier for 2024 was roughly 50% higher than that for 2023. In 2025, pledge growth is currently exceeding 2024 growth (by this time in 2024 we had ~280 new 🔸10% Pledges, so far in 2025 we have ~370 new 🔸10% Pledges), although our costs are also higher. 

> So I wonder whether the information below on GWWC's website is somewhat misleading.

I don't think I agree that the information on the website is misleading seeing as it just states the number of people who have taken the pledge. I think it’s important to bear in mind that the pledge has never required that pledgers record their donations with GWWC and we know that many of our most engaged pledgers do not record their donations.

> I guess pledges starting in later years are less valuable, such that you are overestimating your impact by not controlling for the year the pledge started.


The regression you suggest is something we have considered, but don’t think it is an obvious improvement over our approach of taking the mean over the most recent pledge years. While there might be an effect of the year the pledge started on average first-year pledge donations, we do not think this trend is linear. For instance, the 2021 cohort had the second highest average first-year donations across all cohorts and the five cohorts with the lowest average first-year donations were 2010, 2017, 2018, 2016 and 2012. Ultimately, this is an empirical question and my prediction is that our average method will be more predictive of the first year of pledge donations for the 2024 cohort than the regression. If you are interested in performing this analysis yourself, you can find total inflation-adjusted pledge donations by pledge cohort and year of pledge in a table in this document.


> Have you considered retiring The Trial Pledge? You estimated 96 % of your impact came from The 10 % Pledge.


We currently aren’t considering retiring the 🔹Trial Pledge. While in terms of direct donation value the 🔹Trial Pledge contributes a relatively small fraction of our pledge impact, we believe the main value add of the 🔹Trial Pledge comes from 🔹Trial  pledgers ‘upgrading’ to 🔸10% Pledges. For example, roughly 10% of those who have taken a 🔹Trial Pledge are now 🔸10% Pledges and we are currently exploring ways to improve conversion rates even more. We have also seen some evidence that retention may be stronger for 🔸10% Pledges that follow 🔹Trial Pledges than for other 🔸10% Pledges.

Vasco Grilo🔸 @ 2025-06-13T13:41 (+3)

Thanks for the feedback, Aidan! Strongly upvoted.

I would actually expect our marginal multiplier to be much closer to our average multiplier than the CEARCH method implies.

What is your best guess for the marginal multiplier of donating to GWWC now? I think it would be great if you estimated GWWC's marginal multiplier in your next impact evaluation. Do you plan to publish this in 2026, looking into your impact in 2025? I guess data until the end of 2025 would be enough for you to have a better idea about your marginal multiplier.

I don't think I agree that the information on the website is misleading seeing as it just states the number of people who have taken the pledge.

Assuming the median person who checks your website, and reads the sentence I quoted above[1] believes something like 90 % of pledgers are fulfilling their pledges, but that in reality only 1/3 are actually fulfilling it based on recorded and non-recorded donations, would you agree it would be better to update the website such that people do not think the size of the active community is much larger than it actually is? If you do agree, which fraction of pledgers are fulfilling their pledge based on past recorded and non-recorded donations? I understand there is uncertainty, but your estimate that only 59.4 % of 10 % Pledgers record a donation in the 1st year of their pledge makes me think the fraction of people fulfilling their pledges could me much lower than what people checking your website think. I think you should at least update the sentence I quoted above from your website to something like the following. "9,840 people have pledged to donate at least 10% of their net income". I suspect many will infer from the words "community" and "pledging", which GWWC is currently using, that the vast majority of pledgers are fulfilling their pledge.

The regression you suggest is something we have considered, but don’t think it is an obvious improvement over our approach of taking the mean over the most recent pledge years. While there might be an effect of the year the pledge started on average first-year pledge donations, we do not think this trend is linear.

I still think assuming a (potentially small) linear effect of the year the pledge started on donations is better than supposing no effect at all. The effect may be non-linear, but I see this as a reason for running a non-linear regression (e.g. D(s, y) = a(s) + b(s)*y + c(s)*y^2), not for supposing an effect of 0.

For instance, the 2021 cohort had the second highest average first-year donations across all cohorts and the five cohorts with the lowest average first-year donations were 2010, 2017, 2018, 2016 and 2012.

Note the year the pledge started can affect donations in years of the pledge besides the 1st.

We currently aren’t considering retiring the 🔹Trial Pledge. While in terms of direct donation value the 🔹Trial Pledge contributes a relatively small fraction of our pledge impact, we believe the main value add of the 🔹Trial Pledge comes from 🔹Trial  pledgers ‘upgrading’ to 🔸10% Pledges.

Have you estimated the fraction of the impact you attributed to The 10 % Pledge which was caused by The Trial Pledge?

For example, roughly 10% of those who have taken a 🔹Trial Pledge are now 🔸10% Pledges

Note many of these pledgers might have taken The 10 % Pledge anyway, just slightly later than they would have without The Trial Pledge.

  1. ^

    Our community includes 9,840 lifetime members pledging ≥10% of their income, plus 1,117 trial pledgers, together making up our 10,957 strong giving community

Aidan Whitfield🔸 @ 2025-06-25T01:45 (+7)

Hi Vasco, thanks for your response! Sorry for my delay in getting back to you, I have just got back from leave. I have tried to leave responses to your main points below, but if I have missed anything please let me know.

Re: our marginal multiplier: This is not something we have explicitly tried to model. The most relevant information I can provide here is that our bar for undertaking new pledge acquisition activities is that they must at least exceed 5x in expectation, but this is still not the same as our marginal multiplier for a number of reasons. While we hope to publish an estimate of our average multiplier for 2025 in early 2026, I currently don’t expect to try to explicitly estimate our marginal multiplier. One key reason for this is that, unless we have identified a very scalable method for growing pledges, our marginal multiplier estimate would change quite quickly as we receive more funding and so may only be relevant for a brief period.

Re: how we report the number of pledgers on the website: Thanks for sharing your thoughts here! I continue to think that the statement on our website is accurate and that it isn’t misleading to use the terms ‘community’ and ‘pledging’ here. Simply, these are the numbers of people in our community who have taken pledges with GWWC. I don’t believe the text makes a claim about the number of pledgers who are reporting their donations (which is not a requirement of the pledge) or the number who are fulfilling their pledge (which we don’t have a reliable estimate of). It isn’t clear to me why we should think that the median person who reads the statement would assume that 90% of pledgers are donating.

Re: modelling pledge value for different cohorts: This kind of regression modelling will be something we continue to consider implementing in future evaluations, but currently it isn’t clear enough to me that these models will be better predictors of future cohort pledge donations than the 'average of recent years' method we currently use. The trends to date have simply been too noisy for me to feel confident in any given mathematical model. I also think these models involve some tradeoffs in terms of time investment and legibility and that we also need to factor in these considerations when selecting our approach.

Re: Trial Pledges:  We have not estimated the fraction of impact we attribute to the 🔸10% Pledge that was caused by the 🔹Trial Pledge, but I would roughly guess for recent cohorts it is somewhere in the vicinity of 5–20%. It is difficult to come up with a precise estimate because we don’t know how causally responsible the 🔹Trial Pledge is for the 🔸10% Pledge in these cases (as you note).

Vasco Grilo🔸 @ 2025-06-25T10:10 (+5)

Thanks, Aidan!

While we hope to publish an estimate of our average multiplier for 2025 in early 2026

Great to know!

I currently don’t expect to try to explicitly estimate our marginal multiplier. One key reason for this is that, unless we have identified a very scalable method for growing pledges, our marginal multiplier estimate would change quite quickly as we receive more funding and so may only be relevant for a brief period.

I think estimating in early 2026 GWWC's marginal multiplier in 2025 would still be useful. A value higher than 1 would suggest GWWC should have received more funding this year.

The marginal multiplier should ideally not vary much across years. GWWC should move funds from the years with the lowest marginal multiplier to the years with the highest marginal multiplier until the marginal multiplier is the same across all years. If you estimated your marginal multiplier annually, you could realise you should have spent more/less if you marginal multiplier decreased/increased.

Ramiro @ 2025-06-12T14:29 (+3)

Reading this made me want to revoke my GWWC pledge (or at least cancel my account). I've been a pledger since 2018, and I will continue donating at least 10% of my income to the charities I find most effective and register it on a spreasheet. I just don't think it is appropriate that GWWC's operations take more credit than it's due for whatever good comes from this, and I would like to be sure they are not using my data - as I doubt that donation records go through rigorous reconciliation. I'd probably already have done it if GWWC webpage allowed it - at least I can find no "delete my account button".

Aidan Whitfield🔸 @ 2025-06-13T11:14 (+9)

Hi Ramiro, thanks for sharing your concerns. In my response to Vasco’s comment, I explain why I don’t think our communications around the number of people who have signed the pledge is misleading. As for whether we take more credit than is due for pledge donations, I want to flag two important ways we try to ensure we aren’t overestimating our impact (among others): 

  1. We do not take credit for donations not recorded on the platform unless we have evidence from our surveys that additional pledge donations occurred (see our recording coefficient).
  2. We only take credit for pledge donations that our survey of pledgers indicates we are causally responsible for (see our counterfactuality coefficient). In this impact evaluation, we estimated that we caused 33% of pledge donations.

If this is still your preference, you can resign from your pledge using this form. I hope I have understood your concerns, but please let me know if you have any further questions or concerns.

Vasco Grilo🔸 @ 2025-06-12T16:18 (+2)

Hi Ramiro,

Would you still be concerned if GWWC just reported the total recorded donations in $, and the number of pledges being fulfilled based on recorded donations? I agree the way they are reporting the number of pledgers should be updated, and I had expressed my concerns about this 14 months ago (I have added the email I sent them then to my previous comment). However, I do not think GWWC is taking undue credit in their cost-effectiveness analyses.

Deco 🔹 @ 2025-06-15T10:13 (+5)

Our best-guess estimate of GWWC’s giving multiplier for 2023–2024 was 6x, implying that for the average $1 we spent on our operations, we caused $6 of value to go to highly effective charities or funds. 

 

The Centre for Exploratory Altruism Research (CEARCH) estimated GWWC's marginal multiplier to be 17.6 % (= 2.18*10^6/(12.4*10^6)) of GWWC's multiplier. This suggests GWWC's marginal multiplier from 2023 to 2024 was 1.06

 

Why is there such a large difference between these multipliers?

After googling I think I understand a marginal multiplier is what the next dollar donated to GWWC returns but would like to clarify and post this so others such as myself don't mistake this as a large reporting discrepency.

If I'm understanding the marginal multiplier correctly I would also be interested as to why the return on the next dollar donated is so much lower than the return on the average dollar donated.

Mo Putera @ 2025-06-16T03:44 (+4)

Aidan's response to Vasco's comment you quoted is a starting point:

I would actually expect our marginal multiplier to be much closer to our average multiplier than the CEARCH method implies. Most importantly, I expect most of our marginal resources are dedicated to identifying and executing on scalable pledge growth strategies. I think this work, in expectation, provides a pretty strong multiplier. By comparison our average multiplier includes some major fixed costs (e.g., related to running our donation platform). 

anon animals @ 2025-06-11T09:07 (+5)

What % of people who take the pledge actually report their donations to you/ pledge directly through GWWC? do you only assume impact for the ones who report donations or do you also infer their impact through those who report donations? 

Mo Putera @ 2025-06-12T09:04 (+7)

(The recording coefficient section of their report discusses this extensively if I've interpreted your question correctly.)