Boris pointed me to this book by Arthur Brooks, who looked at statistics on charitable giving from several surveys between 1996 and 2004. Some findings:
On average, religious people are far more generous than secularists with their time and money. This is not just because of giving to churches—religious people are more generous than secularists towards explicitly non-religious charities as well. They are also more generous in informal ways, such as giving money to family members, and behaving honestly.
The nonworking poor—those on public assistance instead of earning low wages—give at lower levels than any other group. Meanwhile, the working poor in America give a larger percentage of their incomes to charity than any other income group, including the middle class and rich.
A religious person is 57% more likely than a secularist to help a homeless person.
Conservative households in America donate 30% more money to charity each year than liberal households.
If liberals gave blood like conservatives do, the blood supply in the U.S. would jump by about 45%.
I have a few quick thoughts:
1. These findings are interesting partly because they don’t fit into any simple story: conservatives are more generous, and upper-income people are more conservative [typo fixed; thanks, Dan], but upper-income people give less than lower-income people. Such a pattern is certainly possible–in statistical terms, corr(X,Y)>0, corr(Y,Z)>0, but corr(X,Z)<0)--but it's interesting. 2. Since conservatives are (on average) richer than liberals, I'd like to see the comparison of conservative and liberal donations made as a proportion of income rather than in total dollars. 3. I wonder how the blood donation thing was calculated. Liberals are only 25% of the population, so it's hard to imagine that increasing their blood donations could increase the total blood supply by 45%. 4. The religious angle is interesting too. I'd like to look at how that interacts with religion and ideology. 5. It would also be interesting to see giving as a function of total assets. Income can fluctuate, and you might expect (or hope) that people with more assets would give more. We're looking forward to getting into these data and making some plots. (Boris suggested the secret weapon.)
P.S. Bruce McCullough points out Jim Lindgren’s comments here on the study, questioning Brooks’s reliance on some of his survey data.
P.P.S. Also see here for more of my thoughts.