Bryan Caplan  

A Little Evidence I'm Wrong About Voter Motivation

The Blogging Meme... More on the Reformation...

I disbelieve what I call the Self-Interested Voter Hypothesis (SIVH for short). Political scientists like David Sears have amassed a mountain of empirical evidence against the SIVH, and the evidence on the other side (mostly economists, I'm afraid) is awfully weak.

When I say that, I don't mean that that the SIVH occasionally fails to work. I mean that it virtually never works. Knowing someone's objective self-interest tells you essentially nothing about his political beliefs. To take the easiest example, it is simply not true that Democrats are poor and Republicans are rich. The correlation between income and party is very close to zero. I've run lots of regressions myself on two unrelated data sets. It checks out.

However, Alex Tabarrok recently brought a little counter-evidence to my attention. According to the Statistical Modeling, Causal Inference, and Social Science blog, here is the individual-level income/vote breakdown from exit polls for the 2004 presidential election:

Income    %R    %D
<$15K     36%   63%
$15-30K   41%   58%
$30-50K   48%   51%
$50-75K   55%   44%
$75-100K  53%   46%
$100-150K 56%   43%
$150-200K 57%   43%
>$200K    62%   37%

Is it time to reverse my position? Not given all the other evidence I've seen. But it IS time to get a little less sure, and wonder about the source of the disparity. My main thoughts:

1. The vote share is very flat from $50K-$200K. And since perhaps 1% of families make over $200K, they wouldn't have any discernable effect on the income-party correlation. So maybe the individual-level correlation from exit polls is not that far from what I've seen before (around .05).

2. The results I know well are for party identification, not vote. Could presidential vote be more selfish than your choice of party?

3. Presumably personality matters more in presidential races than in any other electoral contest. That adds a lot of noise, so perhaps it is not so surprising that the results are different than for party ID. Still, the implication is that Republicans making less than $50K were unusually likely to vote against their party. Is that credible?

4. The results I've seen are for the whole population, not just voters. Could voters fit the SIVH better than non-voters? I've looked at this issue before, however, and found no evidence of it.

Many people dislike empirical work because it never gives you a definite answer. That doesn't stop you, however, from being nearly definite. I get less confident when a little counter-evidence comes in, but it would take a lot more to drastically change my mind. As one of my favorite sayings goes: "Keep an open mind - but not so open that your brain falls out of your head."

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TRACKBACKS (6 to date)
TrackBack URL:
The author at Statistical Modeling, Causal Inference, and Social Science in a related article titled Rich state, poor state, red state, blue state: who's voting for whom in Presidential elections? writes:
    Higher-income states support the Democrats, but higher-income voters support the Democrats. This confuses a lot of people (for example, see here and here). Boris presented our paper on the topic at the Midwest Political Science meeting last weekend. He... [Tracked on April 10, 2005 8:20 PM]
The author at The Left Coaster in a related article titled Wealth and Voting: No Real Surprise writes:
    Alex Tabarrok at Marginal Revolution (via Brad DeLong) says: Statistical Modeling, Causal Inference, and Social Science is one of my favorite new blogs. It is primarily written by Andrew Gelman, a professor in the Departments of Statistics and Politica... [Tracked on April 17, 2005 6:26 PM]
COMMENTS (16 to date)
John Thacker writes:

2. The results I know well are for party identification, not vote. Could presidential vote be more selfish than your choice of party?
Still, the implication is that Republicans making less than $50K were unusually likely to vote against their party. Is that credible?

Hypothesis-- Perhaps party registration is fixed at an early age, and people are reluctant to change. Republicans making less than $50K might disproportionately consist of young voters (say college students and grad students) registering for the same party as their parents, but then not voting that way, and older voters remaining in the same party even when no longer working but now dependent on Social Security and thus with a lower income. In the South, of course, there are plenty of examples of people registering as Democrats because their family has always been Democrats, but then not voting that way. There are also NorthEastern Republicans that vote Republican locally but not nationally, and similarly for Democrats especially in the South.

spencer writes:

I'm bothered by the point that these data sum to 100. In other words everone is either a D or a
R. What about independents? Clearly over the last quarter century the growing number of voters that do not identify with either of the two parties is not reflected in this data set.

Dave Peterson writes:

Great post Bryan. I'm gonna have to go read those pdfs you linked to.

Randy writes:

Not sure I see where you are going with this.Are you saying there's a difference between Democrats and Republicans?

Robert Schwartz writes:

A couple of observations.

First, much of American politics is about group identification (ethnic, regional, occupational, etc.) Jews vote very heavily Democrat, no matter what their economic status, as do blacks. Other examples abound.

Second, the link between parties (or candidates), policies and self interest is a lot less clear than Thomas Frank would have us believe. Do I want to tax the rich if I am not rich? It might depend on whether I believed that increased taxes would make me lose my job. Argument and experience may be 2 different things. Republicans can argue that lowering taxes producees prosperity, but Democrats can say that raising taxes in the early 90s produceed the boom of the late 90s. If I am heavily invested in the stock market I might accept their the Democrat position on the basis that it is better to have a boom with higher taxes than a bust with lower taxes.

Jason Ligon writes:

I don't know how to test it, but my pet hypothesis is that 'self interest' governs voting decisions to a great extent, but what that means is non obvious.

I once heard Grover Norquist comment that everyone is a one issue voter. That thing that motivates you to get up and vote is not a broad ideology, it is your One Big Thing. In that context the dollars party affiliation by income bracket sort of presumes that dollars are the one big thing. Check NOW voters of any income bracket vs. Republican voters. Check NRA members vs. Democrat voters. This second may not be a good example, because gun owners often feel torn between union support from the left and gun rights on the right. You get the idea.

DeadHorseBeater writes:

I'm bothered by the phrase "objective self interest". What kind of economist can write such a phrase... are we now going to be running around, measuring people's cardinal utility in units of Utils?

Suppose there were such a thing, as measured by post-tax, post-transfer EPDV of lifetime wealth, weighted by some utility function which takes risk aversion, the rate of intertemporal substitution, and dynastic altruism into account.

Even as a a pro-free-market guy, I'm not sure which party would maximize that objective self-interest, even if you told me what my values of those preference parameters were.

Adrian writes:

Spencer: In this case, R and D actually mean Bush and Kerry.

Two other points:
1) When I check exit polls for individual states, correlation between income and vote ranges from very strong, e.g. Texas
to small, e.g. New Jersey
to essentially non-existant, e.g. Washington state
2) The income distribution in exit polls is:
3% >200K
4% 150-200K
11% 100-150K
Are some people exaggerating their income in exit polls? According to US census office, only 0.7% population has income >200K.

David Peterson writes:

Are some people exaggerating their income in exit polls? According to US census office, only 0.7% population has income >200K.

Or lying on their tax returns. It could also be that they are more likely to vote than those who make much less.

El Presidente writes:

It's more than a little evidence.

I have no doubt that voters believe they are voting in their own self-interest but two problems complicate the job of calculating one's best available option and interpreting voter behavior.

1. Complexity of the issues that concern voters
This includes whether or not government should engage a particular problem, the best level of government to deal with the issue, and the best policy; 3 very hard decisions.

2. Confusion of intended and actual outcomes
Ridiculous promises. Broken promises. Unintended consequences.

Our government often gets a pass on these because of its form (Democratic Republic). We’ve consolidated democracy into a group exercise of the fallacies of Argumetum ad Hominem, and others. Woodrow Wilson, the only Political Scientist to become president (1913-1921), advocated a parliamentary system ostensibly to make government more responsive and voter expression more definite. I don't agree with his suggestion, or that the results would necessarily be preferable. However, I hope this demonstrates that the issue isn't new. It's genuinely difficult to determine what on Earth people are thinking when they vote but it is fairly certain that they are all thinking different things, with some commonality between them. Fewer producers will shift supply to the left. This is no less true with public goods than it is with widgets. The number of producers (2 if you count by parties, 3-4 if you count by levels of governmental jurisdiction) does not provide great enough breadth to accurately assess the wide range of consumer preferences in the market of public goods. My preferred option for greater diversity is the expansion of NGO public goods producers.

The timeless wisdom of my favorite islander:
Democracy is the worst form of government except for all those others that have been tried.
~Winston Churchill

Austin writes:

I think the question should be, how to measure self interest. For most people, their ideology is very important. Laws which support their ideology (or don't suppress their idology) have a big impact on their happiness.

A better question might be, is voting for your ideology voting for self interest? Many christians (myself included) vote for particular candidates because of the candidates beliefs.

Economists sometimes think they can measure self-interest soley in terms of money. There are many areas of self-interest that can't be bought.

guerby writes:

Eh eh, are you racing for funny logic? "Many people dislike empirical work because it never gives you a definite answer", I assume "Many people disklike theory work because it never gives you a definite answer", conclusion "Many people dislike work since it never gives you a definite answer", people here being economists of course :) :).

Adrian: 4 times higher turnout for >200k income than on the rest of the population may be?

Nicholas Weininger writes:

You yourself said (in the linked notes) that race and gender were much better predictors of voting behavior than income per se. Are there exit poll numbers that break down by income among a specific race/gender category (e.g. white females)?

If, for example, people earning less than 30K are very disproportionately black and/or female, that would make the data set much less striking.

spencer writes:

When you look at the post WW II economic record with such data points that under Democrats the average annual increase in the stock market has been 12% and under Rebublicans it has been 7.3%. You get the same type of comparison for real GDP growth . Under Republican it has averaged 3.3% as comparded to 4.4% under Democrats.

So if you economic well being is dependent on how well the stock market or economy do it is to your self interest to vote Democratic not Republican.

Your basic premise that it is the economic interest of the well to do to vote Republican is highly questionable.

Nathan Smith writes:

I don't believe that voters are self-interested (after all, the really self-interested thing to do is to stay home). But income could be correlated to Bush/Kerry voting because it's correlated to values. People who make larger incomes are likely to appreciate, first-hand, that lower taxes reduce labor incentives. They know something about the people who really make capitalism run, and about what motivates them. The tax cut will seem like a useless giveaway to a person making under $50,000. "That much money is just surplus," such a voter will think. "There's no harm in taxing it away." The person earning $200,000 knows he would work less if he were taxed more, and that others would suffer for it.

Adrian writes:

I realized I have misinterpreted the exit poll data in my previous comment. The income numbers in exit poll are family income.

That explains why the % of high-income people in exit poll is much higher than in census data. I was comparing census data for INDIVIDUALS with exit poll data for FAMILIES. My mistake.

Now, we know that married people voted for Bush in much larger numbers (57% married vs. 40% for singles, by the same exit poll). Married families are also likely to have higher incomes than singles. That certainly explains part of the income-vote correlation. I wonder how much of correlation is left, after we account for that.

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