Three word explanations

Median voter theorem.

It's my first-cut account of a lot of what is going on in the newspaper headlines.  Yet somehow I rarely see it mentioned, even when I read very prominent social scientists commenting on current policy.

I thank Garett Jones for a useful conversation behind this blog post.


When I was TAing Microeconomics last fall, I could not find any good and intuitive explanation of median voter theorem online or in a microeconomics textbook. It was very frustrating. I would find articles in Econ or Public Policy journals with lots of math, but not one intuitive explanation. Could you point to any sources to read up on it?

There's a great discussion of the Median Voter Theorem in the third lecture from Yale's open course on game theory:

Here's the full Krugman column, by the way, with more details on why he believes the median Senator is very different than the median voter w.r.t. health care and especially the "public option":

See also this poll or similar polls summarized by Nate Silver recently:

SGS about the median voter or the median Senator? When the politicians and their lackeys start trotting out the polls, especially those as contradictory as the NYT poll...

"While 85 percent of respondents said the health care system needed to be fundamentally changed or completely rebuilt, 77 percent said they were very or somewhat satisfied with the quality of their own care."

"Three of four people questioned said unnecessary medical tests and treatments had become a serious problem, suggesting that they would support calls by health researchers for a payment system that would better reward appropriate care. But an even higher number, 87 percent, said the inability of people to have the needed tests and treatments was a serious problem."'s a clue that they are substituting populism in place of principle and accuracy.

"Half of those questioned said they thought government would be better at providing medical coverage than private insurers, up from 30 percent in polls conducted in 2007. Nearly 60 percent said Washington would have more success in holding down costs, up from 47 percent."

Damn, the gov't got a lot better in 2 years.

Tyler, do you disagree with Paul Krugman about the preferences of the median voter in the U.S. or do you mean the theorem to apply to the median senator (or median lobbyist) instead?

He's quoting the parts of the polls that shows that people want free stuff, but not the parts that show that they don't want to pay for it.

In addition, student, you can note from various polls that one of the things that people emphatically say in polls that they don't want are precisely the types of cost controls and equalization of spending that the studies seem to suggest that we should do and could do without harming care.

It's easy to cherry-pick part of the polls. What's generally true:

* People would like to cover the uninsured, but
* They don't want their own coverage to be changed (leading Obama to overpromise that no one will lose employer coverage against their will under his plan, something that can't be done with an efficient and cost-effective plan)
* People don't want to pay more in taxes or pay more for treatment or insurance premiums, but
* They don't want any claim to be denied, even if science demonstrates that it's useless or that their area spends 30% more for no better care.
* They agree that there are unnecessary spending and tests, but
* Certainly not anything that their doctor would ever recommend.
* They trust the government more than insurance companies to hold down costs, but
* Their idea of how to hold down costs is not at all what Orszag is proposing.

The median voter is either irrational, or believes that health care costs are all a conspiracy.

My three word explanation

Something for Nothing

can be reduced to the two word explanation

Free Lunch

While the recent survey indicated that a majority said they would support paying more in taxes to cover the un/under-insured, I'm not convinced that a majority won't continue voting for politicials denouncing high taxes and promising to cut taxes (justified of course by unspecified fiscal responsibility of cutting waste, fraud, and entitlement reform).

A more serious three word explanation is

Not Evidence Based

The headlines denounce Obama's attempt to take control of your health care so he can ration it and cause your health to suffer. Or the claim that government run health care costs more and is inferior to our health care system, which gives superior care to everyone and is cheaper than in Canada and Britain.

Median voter theorum is a model that in a democracy, the preferences of the median voter become policy for the nation (because they are the only policies that can attract enough support to pass with a majority).

I think the status quo policy matters quite a lot these days. I would argue that becuse the Democrats control everything, the proposed policies are going to start at the median Democrat and schooch to the right until the conservative Dems like the proposed policy more than the status quo. Since most established policies are probably at or to the right of the median Congressman right now, it's going to be a hard sell moving those too far to the left. The status quo default option for climate change and health care may well kill legislation. On something like financial markets where the current policies might be seen as on the far right, we will might see reform land closer to the median Dem than the median voter.

If, in fact, Democratic senators are positioning themselves to the right of the median voter, perhaps a modified version of the model provides the best explanation. (I'm not saying that the premise is true -- as John Thacker ably notes, the "typical voter" as revealed through polls is so confused and self-contradictory that it's almost meaningless.)

The two modifications are:

1. There are massive institutional barriers to challenging an incumbent for the nomination. We can model this by assuming that even if a Democratic candidate is to the right of the median, there is only a small chance p(x) that a challenger is able to slip in on the left, where p is an increasing function of x, the distance from the median.

2. The distribution of voters is dynamic and partially unpredictable.

With these two modifications, you can continue to explain the vast majority of political behavior as strategic positioning along a one-dimensional continuum of ideology, but many of the apparent paradoxes disappear. If there is only a small chance that a liberal challenger will capitalize on a Democratic nominee's slight rightward drift (modification 1), it may be optimal for a Democratic incumbent to place himself to the right of the median to hedge against the risk that the median might move to the right in the future. (modification 2).

Here's another survey of poll results by William Galston showing that, to a first approximation, what the average American wants health care reform to do could be better approximated by taking what Orszag and other experts are proposing and doing exactly the opposite.

See also the Kaiser CEO's The Experts versus the Public on Health Care Reform.

Democrats realize that while certain broad ideas poll well, the public's idea of the details are very different from the experts'. So even something that might be good in the long run may be punished heavily at the polls in the short-run.

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