Hi Vasco, thanks for your engagement! I have put together some responses to your questions/âcomments below. Please let me know if I missed anything or you have further questions.
> The Centre for Exploratory Altruism Research (CEARCH) estimated GWWCâs marginal multiplier to be 17.6 % (= 2.18*10^6/â(12.4*10^6)) of GWWCâs multiplier. This suggests GWWCâs 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 GiveWellâs 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).
Itâs 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 đ¸10% Pledges, so far in 2025 we have ~370 new đ¸10% Pledges), although our costs are also higher.
> So I wonder whether the information below on GWWCâs website is somewhat misleading.
I donât 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 itâs 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 donât 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 arenât considering retiring the đšTrial Pledge. While in terms of direct donation value the đšTrial Pledge contributes a relatively small fraction of our pledge impact, we believe the main value add of the đšTrial Pledge comes from đšTrial pledgers âupgradingâ to đ¸10% Pledges. For example, roughly 10% of those who have taken a đšTrial Pledge are now đ¸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 đ¸10% Pledges that follow đšTrial Pledges than for other đ¸10% Pledges.
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 GWWCâs 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 donât 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 1â3 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. â9,840 people have pledged to donate at least 10% of their net incomeâ. I suspect many will infer from the words âcommunityâ and âpledgingâ, 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 donât 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 arenât considering retiring the đšTrial Pledge. While in terms of direct donation value the đšTrial Pledge contributes a relatively small fraction of our pledge impact, we believe the main value add of the đšTrial Pledge comes from đšTrial pledgers âupgradingâ to đ¸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 đšTrial Pledge are now đ¸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.
Our community includes 9,840 lifetime members pledging âĽ10% of their income, plus 1,117 trial pledgers, together making up our 10,957 strong giving community
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 donât 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 isnât misleading to use the terms âcommunityâ and âpledgingâ here. Simply, these are the numbers of people in our community who have taken pledges with GWWC. I donât 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 donât have a reliable estimate of). It isnât 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 isnât clear enough to me that these models will be better predictors of future cohort pledge donations than the âaverage of recent yearsâ 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 đ¸10% Pledge that was caused by the đšTrial Pledge, but I would roughly guess for recent cohorts it is somewhere in the vicinity of 5â20%. It is difficult to come up with a precise estimate because we donât know how causally responsible the đšTrial Pledge is for the đ¸10% Pledge in these cases (as you note).
While we hope to publish an estimate of our average multiplier for 2025 in early 2026
Great to know!
I currently donât 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 GWWCâs 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/âless if you marginal multiplier decreased/âincreased.
Hi Vasco, thanks for your engagement! I have put together some responses to your questions/âcomments below. Please let me know if I missed anything or you have further questions.
> The Centre for Exploratory Altruism Research (CEARCH) estimated GWWCâs marginal multiplier to be 17.6 % (= 2.18*10^6/â(12.4*10^6)) of GWWCâs multiplier. This suggests GWWCâs 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 GiveWellâs 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).
Itâs 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 đ¸10% Pledges, so far in 2025 we have ~370 new đ¸10% Pledges), although our costs are also higher.
> So I wonder whether the information below on GWWCâs website is somewhat misleading.
I donât 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 itâs 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 donât 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 arenât considering retiring the đšTrial Pledge. While in terms of direct donation value the đšTrial Pledge contributes a relatively small fraction of our pledge impact, we believe the main value add of the đšTrial Pledge comes from đšTrial pledgers âupgradingâ to đ¸10% Pledges. For example, roughly 10% of those who have taken a đšTrial Pledge are now đ¸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 đ¸10% Pledges that follow đšTrial Pledges than for other đ¸10% Pledges.
Thanks for the feedback, Aidan! Strongly upvoted.
What is your best guess for the marginal multiplier of donating to GWWC now? I think it would be great if you estimated GWWCâs 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.
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 1â3 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. â9,840 people have pledged to donate at least 10% of their net incomeâ. I suspect many will infer from the words âcommunityâ and âpledgingâ, which GWWC is currently using, that the vast majority of pledgers are fulfilling their pledge.
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.
Note the year the pledge started can affect donations in years of the pledge besides the 1st.
Have you estimated the fraction of the impact you attributed to The 10 % Pledge which was caused by The Trial Pledge?
Note many of these pledgers might have taken The 10 % Pledge anyway, just slightly later than they would have without The Trial Pledge.
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 donât 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 isnât misleading to use the terms âcommunityâ and âpledgingâ here. Simply, these are the numbers of people in our community who have taken pledges with GWWC. I donât 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 donât have a reliable estimate of). It isnât 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 isnât clear enough to me that these models will be better predictors of future cohort pledge donations than the âaverage of recent yearsâ 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 đ¸10% Pledge that was caused by the đšTrial Pledge, but I would roughly guess for recent cohorts it is somewhere in the vicinity of 5â20%. It is difficult to come up with a precise estimate because we donât know how causally responsible the đšTrial Pledge is for the đ¸10% Pledge in these cases (as you note).
Thanks, Aidan!
Great to know!
I think estimating in early 2026 GWWCâs 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/âless if you marginal multiplier decreased/âincreased.