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Larks comments on CEA does not seem to be credibly high impact - Less Wrong Discussion

10 Post author: Jonathan_Lee 21 February 2013 10:29AM

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Comment author: Larks 21 February 2013 11:11:47AM 2 points [-]

The GWWC site, for example, claims that from 291 members there will be £72.68M pledged.

Qn: On what basis does GWWC assert that its near 300 members are credibly precommitted to donating £72.68M?

While I don't know what the official answer would be, I think there is basically a linguistic one. To have pledged does not require one to have credibly precommitted. I can pledge to resist torture for 40 days just by saying so, but this doesn't mean I've credibly precommitted to doing so.

Of course, this only clears GWWC of accusations of excessive optimism. The question of how many members will maintain the pledge remains, and I don't see how we can get a very good idea for a few years (untill we have enough data points to extrapolate the perameters of the distribution).

Comment author: Jonathan_Lee 21 February 2013 11:40:35AM 2 points [-]

In that case, having a claim on every page of the GWWC site claiming that £112.8M have been pledged seems deceptive. 291 people have pledged, and [by a black box that doesn't trivially correspond to reality] that's become £112.8M. I know that at least 3 people in Cambridge have seen that statistic and promptly laughed at GWWC. The numbers are implausible enough that <5s Fermi estimates seem to refute it, and then the status of GWWC as somewhat effective rational meta-charity is destroyed. Why would someone trust GWWC's assessment of charities or likely impact over, say, GiveWell, if the numbers GWWC display are so weird and lacking in justification?

Comment author: jkaufman 23 February 2013 03:56:59AM 3 points [-]

Do you really think that their pledge total is something other than the (undiscounted) sum of what those 291 people have pledged to give over the course of their lives? You think they're just making it up?

Comment author: Jonathan_Lee 23 February 2013 09:55:44AM -1 points [-]

I do not think that they are "making it up"; that phrase to me seems to attach all sorts of deliberate malfeasance that I do not wish to suggest. I think that to an outside observer the estimate is optimistic to the point of being incredible, and reflecting poorly on CEA for that.

These 291 people haven't pledged dollar values. They've pledged percentage incomes. To turn that into a dollar value you need to estimate whole-life incomes. Reverse engineering an estimate of income (assuming that most people pledge 10%, and a linear drop off in pledgers with 50% donating for 40 years), yields mean lifetime earnings of ~£100K. That's about the 98th centile for earnings in the UK.

Comment author: jkaufman 24 February 2013 03:16:52AM 6 points [-]

These 291 people haven't pledged dollar values. They've pledged percentage incomes.

Ah; I thought that people were pledging a percent and then listing their estimated income. Looking at an old email from gwwc I see in their discussion of pledge calculations:

We lack income data for some people, which we left out, causing an underestimate. Estimate of lifetime earnings by each member for him/herself * percentage pledged by that member, summing over all members who submitted estimates.

which makes me think they are working off of self-reported estimated lifetime incomes. Though they might be extrapolating from people who submitted income amounts to the people who didn't.

a linear drop off in pledgers with 50% donating for 40 years

I don't think that's the right way to interpret "pledge". If 100 people pledge to keep smoking and then only 50 end up going through with it, I would still say that you had 100 pledges.

£112.8M over 291 people and 40 years is ~£10K, or an estimated income of £100K at 10%. (Which is the same number you got, which I think means you didn't actually apply your 50% figure.)

An average income of £100K is high, but looking over their members, remembering that their students are Oxford students, and figuring that people who go into banking or something via EtG might give larger percents (while still having more to keep for themselves) I think their numbers are not "optimistic to the point of being incredible".

Comment author: Larks 22 February 2013 07:35:01PM *  3 points [-]

If someone has pledged to give 10% of X, and you estimate X to be about Y, I think it's not totally unreasonable to suggest Y*0.1 has been pledged, especially if that person doesn't disagree with your estimate of X.