Sunday, October 10, 2010

Oh, economic models…

How applicable, in terms of policymaking, are economic models? It is a question always wrested back-and-forth by economists and policymakers. Here is Laurence Meyer arguing that the new macro-econometric models do no good to advance policymaking realistically.

So I think we have two kinds of modeling traditions. First there is the classic tradition. I was educated at MIT. I was a research assistant to Franco Modigliani, Nobel laureate, and the director of the project on the large-scale model that was used at the time at the Federal Reserve Board. This is the beginning of modern macro-econometric model building. That’s the kind of models that I would use, the kind of models that folks at the Board use.

There’s also another tradition that began to build up in the late seventies to early eighties—the real business cycle or neoclassical models. It’s what’s taught in graduate schools. It’s the only kind of paper that can be published in journals. It is called “modern macroeconomics.”

The question is, what’s it good for? Well, it’s good for getting articles published in journals. It’s a good way to apply very sophisticated computational skills. But the question is, do those models have anything to do with reality? Models are always a caricature—but is this a caricature that’s so silly that you wouldn’t want to get close to it if you were a policymaker?

My views would be considered outrageous in the academic community, but I feel very strongly about them. Those models are a diversion. They haven’t been helpful at all at understanding anything that would be relevant to a monetary policymaker or fiscal policymaker. So we’d better come back to, and begin with as our base, these classic macro-econometric models. We don’t need a revolution. We know the basic stories of optimizing behavior and consumers and businesses that are embedded in these models. We need to go back to the founding fathers, appreciate how smart they were, and build on that.

Krugman responds:

My first reaction, on reading this, was to say that Meyer overstates the case — and he does, a bit. It has been possible to publish New Keynesian models in the journals, and these models do, I think, provide some useful guidance — if only as a consistency check on more ad hoc approaches.

But fundamentally Meyer is right. And it has been going on a long time. By the early 1980s it was already common knowledge among people I hung out with that the only way to get non-crazy macroeconomics published was to wrap sensible assumptions about output and employment in something else, something that involved rational expectations and intertemporal stuff and made the paper respectable. And yes, that was conscious knowledge, which shaped the kinds of papers we wrote. So you could do exchange rate models that actually had realistic assumptions about prices and employment, but put the focus on rational expectations in the currency market, so that people really didn’t notice. Or you could model optimal investment choices, with the underlying framework fairly Keynesian, but hidden in the background. And so on.

[…]So yes: something has gone terribly wrong in macro. And I’m sorry to say that the crisis has only made people dig deeper into their positions.