Sunday, February 1, 2009

Again, I don't have faith in these models and I believe agnosticism is the correct stance.

From Tyler Cowen:

"
Permanent vs. temporary increases in government consumption

Paul Krugman writes:

...he [Brad DeLong] fails to note that it’s not just wrong, it’s 180 degrees wrong: a temporary increase in government spending should have a larger impact on demand than a permanent increase, not a smaller impact.

I intend my comments as the most boring blog post I have written, so it goes beneath the fold...

Perhaps Krugman is drawing from Barro's 1981 JPE paper on government purchases, which does indeed derive the stated result, but that is no longer the dominant approach. Circa 1990, Aiyagari, Christiano, and Eichenbaum note:

First, we demonstrate analytically that -- under standard assumptions spelled out in section 2 below -- the employment and output effects of permanent increases in government consumption always exceed those of temporary increases.

On pp.4-5 they explain why Barro is incomplete.

Overall I find these debates confusing. I wonder for instance if Krugman's blog example is actually comparing tax finance to debt finance, rather than temporary vs. permanent spending shocks. (Note also that Krugman is making a claim about demand or effective "stimulus" rather than output and employment, although I am taking the latter as what matter.)

Those of you with lots of time on your hands can ponder whether the "permanent vs. temporary" debates compare "$100 billion this year vs. $100 billion for each year to come" and/or "$100 billion this year vs. the present value of $100 billion spread out over time, in perpetuity," and whether all cited articles and blog posts are making exactly the same comparisons.

Results in this area usually can be modified by further assumptions. I think of this as the central paper, published in the JME 1999. Admittedly it is for a small open economy but the key result is:

Moreover, permanent increases in government expenditures have larger positive labor supply and output effects than temporary fiscal policies.

Again, I don't have faith in these models and I believe agnosticism is the correct stance. The point is not about who is wrong and who is right but rather how treacherous these analytical waters can be. Beware!

In any case there is hardly an overwhelming brief in favor of the stimulative powers of the temporary spending increase. The best case for the temporary boost is I think the public choice argument that it is better to get it over with more quickly, so as to limit corruption of the government.

Addendum: Megan McArdle adds comments on her contribution to the debate."

And I argue:

Previewing your Comment

"On pp.4-5 they explain why Barro is incomplete."

I would say less useful. The very fact that the model is being improved leads one to believe that the model is useful, but not a complete description, or even causal, of the real world. In our circumstances, it might turn out to be of limited use.

But the same can be said of the multiplier. It seems unreasonable to put so much faith in the precision of any multiplier in this situation, or to simply plug in a consumption figure which needs to be filled.

To me, both approaches seem useful, but not persuasive. The one person I agree with, Shiller, wants us to spend a massive amount of money. I agree that would work, but it could also cause serious inflation, causing us to induce another shock. As well, spending massive amounts of money can influence behavior, but that influence might not all be benign.

And that's my problem with your NY Times post: In order for behavior to be changed in a meaningful way, the influence upon it must be large and long lasting. I think that you underplay the possible social changes that could go with such a shift. They worry me more than this downturn.

Finally, the actual bill. Here was my plan:
1) $100 Billion Infrastructure Investment
2) $200 Billion Sales Tax Cut or Payroll Tax Cut
3) $100 Billion Tax Cut for Investment
4) Social Safety Net and State Aid ( $ ? )

This is different than the bill, but, if I were the Republicans, I would have asked for something similar to my plan and split the difference, for reasons of Political Economy. It would be better that we have an agreed upon plan, precisely because the social changes going forward could be so unpleasant.

Here, I echo Burke:

"All government, indeed every human benefit and enjoyment, every virtue, and every prudent act, is founded on compromise and barter. "

I think that Burke is someone we should keep in mind during a crisis.

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