Thursday, January 15, 2009

That Pesky Multiplier Effect

Conventional (or at least popular) wisdom is that each dollar of government spending contributes more than a dollar of GDP. Further popular wisdom is that spending has a better multiplier than a tax cut.

But Greg Mankiw thr0ws up several well-taken caveats:

In practice, however, the multiplier for government spending is not very large. The best evidence comes from a recent study by Valerie A. Ramey, an economist at the University of California, San Diego. Based on the United States’ historical record, Professor Ramey estimates that each dollar of government spending increases the G.D.P. by only 1.4 dollars. So, by doing the math, we find that when the G.D.P. expands, less than a third of the increase takes the form of private consumption and investment.
Mankiw goes on to poke further at the popular wisdom on tax cuts:

Textbook Keynesian theory says that tax cuts are less potent than spending increases for stimulating an economy. When the government spends a dollar, the dollar is spent. When the government gives a household a dollar back in taxes, the dollar might be saved, which does not add to aggregate demand.

The evidence, however, is hard to square with the theory. A recent study by Christina D. Romer and David H. Romer, then economists at the University of California, Berkeley, finds that a dollar of tax cuts raises the G.D.P. by about $3. According to the Romers, the multiplier for tax cuts is more than twice what Professor Ramey finds for spending increases.

Why this is so remains a puzzle. One can easily conjecture about what the textbook theory leaves out, but it will take more research to sort things out. And whether these results based on historical data apply to our current extraordinary circumstances is open to debate.
Finally, we also have an obvious question from Arnold Kling:

It is amazing what happens when you assume that you live in a linear world. You say that the multiplier for government spending is 1.57.

Really? Over what range? Think of it this way: at which level of additional government spending would the path of U.S. real GDP be the highest?

(a) $100 billion in spending above the baseline
(b) $1 trillion in spending above the baseline
(c) $100 trillion in spending above the baseline

If you use a constant multiplier of 1.57, the right answer is (c). Yet we know that this is not the right answer. At $100 trillion in additional government spending, the United States would be operating like Zimbabwe, with similar results.

So to talk about "the" multiplier, as if it were linear, has to be wrong at some level. Is the multiplier linear over the range between $100 billion of additional spending and $1 trillion of additional spending? I think that is unlikely. Between, say $400 billion and $800 billion, is the incremental multiplier still in a range between 1 and 2? I worry that it is much lower. I worry that it turns negative somewhere in that range.

Personally, I can't see how all the inflating of the economy doesn't lead to a lot of, well, inflation. It doesn't if you think that there is an offsetting amount of deflation (say, somewhere between $5 and $10 trillion), but we really have no idea, do we?

Might not be a terrible time to buy some gold.

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