Results for “kremer”
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More on Vaccines

Though Alex has already blogged about the Kremer/Snyder paper on vaccines versus cures, there are, I think, a couple of comments worth adding.

According to Kremer and Snyder, monopoly sellers would rather sell cures than vaccines. To get this result, they need some heterogeneity: we all have different probabilities of getting sick (though we all find it equally costly to get sick).

But what if you introduce the opposite kind of heterogeneity? (That is, we all have different costs of getting sick, even though we all face the same probability of getting sick.) Then it’s a nice little exercise for your students to show that the cure and the vaccine are equally lucrative monopolies (ignoring the positive externalities of the vaccine).

A more important observation: In the Kremer/Snyder setup (still ignoring positive externalities), it’s a good thing for sellers to invest in cures rather than vaccines. The reason cures are more profitable is that they in essence allow perfect price discrimination. So with cures, there’s no deadweight loss due to monopoly; with vaccines there is.

The analysis changes if you assume, say, that a vaccine prevents a four-day illness, but a cure only cuts two days off your illness. Then vaccines might or might not be socially preferable to cures—but in that case, willingness-to-pay for vaccines versus cures would double. This gives sellers an incentive to produce vaccines. The incentive isn’t perfect, but it goes in the right direction.

Vaccines: The Long Run

Yesterday I discussed some of the reasons for the current shortage. Today, I will discuss an important paper by Michael Kremer and Christopher Snyder. Kremer and Snyder argue that for the same cost and effectiveness drugs are more profitable to produce than vaccines. As a result, private incentives bias the market against vaccines.

A well known reason is that some people free rider on vaccine provision. When you are vaccinated, I benefit from one less possible transmitter. As a result, some who benefit do not pay. Drugs, in contrast, offer more excludable benefits thereby increasing demand and profits.

Drugs also provide a very natural method for firms to, in effect, price discriminate.

A simple example suffices to illustrate this point. Suppose there are 100 total consumers, ninety of whom have a ten percent chance of contracting the disease and ten of whom have a 100 percent chance. Suppose consumers are risk neutral and are willing to pay 100,000 to be cured of the disease if they contract it. A monopolist selling a vaccine could either charge 100,000 and sell to the ten high-risk consumers or charge 10,000 and sell to all 100 of them. Either way, the monopolist’s revenue is 1,000,000. A monopolist selling a treatment would, in expectation, sell to the nineteen consumers contracting the disease (all ten of the high risk consumers as well as an average of nine consumers from the low-risk group) at a price of 100,000 for a total revenue of 1,900,000, almost twice the revenue from a vaccine.

Damn, that’s clever. I wish I had thought of that.

Having praised Kremer and Snyder I now must say that I am not convinced that the forces they discuss matter very much. First, if the pharmaceutical market is competitive and vaccines pay then they will be produced even when drugs would be more profitable to a monopolist. K&S underestimate the competitiveness of the pharmaceutical market.

Second, my suspicion is that nature and science combine to make it the case that some diseases at some times are better treated by vaccines and other diseases by drugs. K and S’s model works best if there are many cases where drugs and vaccines are close cost-substitutes. Firms then choose drugs even when vaccines would have been more desirable. I think, in contrast, that cost differences will usually exceed the profit differences. On the margin, K and S are correct but suppose vaccines had been subsidized would we today have an AIDS vaccine? I doubt it.

I’m not necessarily against their conclusion, however, that vaccines should be subsidized relative to drugs. It’s sad to say, therefore, that as discussed yesterday we currently do precisely the opposite.

What Colombia can Teach Us

Long-time readers will recall my discussion of Vouchers for Private Schooling in Colombia by Angrist, Bettinger, Bloom, King and Kremer in the Dec. 2002 AER. The paper is especially important because it uses data from a randomized experiment.

Angrist et al. estimate that attending private school increased the probability of finishing eighth grade by 13-15 percentage points or 25 percent. Test scores increased by .29 standard deviations which is equivalent to about an extra year’s worth of schooling which has been estimated to increase yearly wages by 10 percent. Other markers such as teen cohabitation also improved.

Angrist, Bettiner and Kremer are back with a follow-up study that looks at high-school graduation rates and test scores on college-entrance exams.

The results of our follow-up study point to lasting benefits for voucher winners, with substantially higher high school graduation rates and, after adjusting for selection bias, higher test scores among those who took the ICFES exam [a college entrance test, Alex]….The size and persistence of the impact suggests PACES was a cost-effective intervention … there is substantial economic return to high school graduation in Colombia.

Vouchers in Chile and Colombia

Tyler mentioned, following a depressed Brad DeLong, a new paper on education vouchers in Chile that does not find large achievement gains. I have some criticisms of the paper (see below) but I was surprised that neither mentioned the most important recent paper on vouchers, Vouchers for Private Schooling in Colombia by Angrist, Bettinger, Bloom, King and Kremer in the Dec. 2002 AER.

Using data from a randomized experiment, Angrist et al. estimate that attending private school increased the probability of finishing eighth grade by 13-15 percentage points or 25 percent. Test scores increased by .29 standard deviations which is equivalent to about an extra year’s worth of schooling which has been estimated to increase yearly wages by 10 percent. Other markers such as teen cohabitation also improved.

Is this just a case of dueling papers? No, first, unlike Hsieh and Urquiola (HU), the Angrist et al. results are consistent with results found elsewhere. See in particular those found for Catholic schooling in the United States . Second, Hsieh and Urquiola (HU) are good researchers, judging by their paper, but Angrist et al. have a much more convincing research design – results from a randomized trial beat econometric identification any day. Cheer up Brad!

I shouldn’t give the impression that the results are directly comparable, however, as HU are trying to get at the general equilibrium effect of a voucher experiment and Angrist et al. are after the partial equilibrium effect of private schooling. Given the large gains found in the partial equilibrium literature, however, the GE results from HU are not plausible in my view.

Now regarding the HU paper some information is in order. First, there were no vouchers in Chile. Instead, there was public funding of some private schools on a per-student basis. Parents could not apply their voucher to the tuition at a private school of their choice.

Second, HU do not test whether students who transferred to private schools did better than other students – they tested whether aggregate scores (public and private) increased over time as more students attended private schools. Their evidence seems consistent with a nationwide decline in public school quality over time. More generally, I would have liked to have seen some information in their paper on the power of their tests. Given the size of the private sector what sort of gains could would we have expected to see in the aggregate scores and is their technique powerful enough to pick up such gains?

Third, HU claim that “cream skimming” was extensive but I find this difficult to believe because there is no price difference between public and private (voucher-accepting) schools since each was paid the same per-student amount. There are some non-pecuniary barriers but no limits on entry that HU mention.

Fourth, why did private enrollment increase if parents did not perceive a quality improvement? HU mention “freshly painted walls” which I thought was a bit flip – we ought to take revealed preference more seriously.

I do think that the HU study of Chile provides useful information about designing a good voucher program and my priors would have been that the program instituted in Chile, even though not a true voucher program, would have produced a larger effect – thus I learned something from the paper.