Can you manage what you can’t measure?

Disclaimer: I’m not a macroeconomist, but I play one in Principles classes. Feel free to point out my errors in the comments.

Economics is filled with imperfect measures of important concepts. GDP, unemployment rates, and price indices all have significant flaws. Measures of entrepreneurship are even worse.

The Chicago Booth IGM Experts’ Panel recently posted an interesting result about the problems with unemployment:


The question is: “The concept of “maximum sustainable employment” is well defined enough to be used beneficially in economic policymaking.”

That’s 42 economists asked, 34 with an opinion (including “uncertain”), and about half of the sentiment is positive. And that sounds about right to me. I read this question as “can we engage in macroeconomic policy that doesn’t do long-run harm?” And if I were to describe my opinion probabilistic, it would look like these results. We could probably do “good policy” with a low degree of precision (i.e. useful enough for severe situations) if 1) we magically didn’t have to deal with political squabbling and 2) explicitly limited our goals to the short run.

Respondents agreeing emphasize that it’s “good enough.” But what does that mean? What level of precision and control are we looking at here?

Here’s the basic situation: given the underlying economic reality (everyone’s individual preferences, capabilities, knowledge, etc.) it makes sense to have some limited number of unemployed people at any given time. Unemployment rate is a measure of “how far are we from 0,” not, “how far are we from the ideal level?” That raises the following questions:

  • How accurately can we know what’s going on in the world?
  • How accurately can we know what’s supposed to be going on in the world?
  • How precisely can we affect the world?

The aggregate macroeconomic theory and empirics of the 1960’s were seriously imprecise. Trying to target macroeconomic policy would be like doing eye surgery with a hand grenade. In that sort of world, your best medicine is probably chicken soup and bed rest.

Here in the present we have much better data and computation. And it’s going to get better. Facebook already has data precise enough to track the exact effects of policy down to the individual level.

But think about a precise outcome and imagine what sort of policy would be required to get there. Let’s say our outcome is “get Rick to buy a new car.” Some mix of low interest rates, the right set of subsidies, and ideal circumstances might move things in that direction. But that sort of surgical outcome is just never going to be possible through legitimate macroeconomic policy (and definitely not monetary policy*). The size of the problem just means that Butterfly Effect problems will prevent macroeconomic policy from having household-level precision, even if the data could (in principle) measure the effect.

Less precise outcomes seem plausible (e.g. “get middle class households in the north east to buy 30-60,000 new cars”), but not without making a lot of second order problems. It’s not so much a “middle of the road leads to socialism” situation as a multiplier effect from a convergent series. Push a billion over there, create big distortions, follow those up with medium distortions, and finally let small remaining problems fizzle out on their own. Throw in public choice issues and it seems obvious that the efficiency cost of precise interventions won’t scale up nicely.

We’re now in a world where our theoretical and empirical tools are more precise than our implementation tools. We’re no longer trying to do surgery with a hand grenade. But that doesn’t mean we’ve got a laser scalpel either. It’s more like we’ve got we’ve got laser-like measuring tools but our implementation tools are blunt objects. If we aren’t careful, we’ll spend our time swatting flies with sledge hammers.

All told, it seems possible that we could engage in fairly targeted macroeconomic policy. But as the scale increases, the marginal cost will rise rapidly (maybe less so with the right institutions). Better timing might increase the effectiveness of each dollar spent*, but overall, it seems like things have to be really bad before the government should consider anything too ambitious.

Manage an economy’s economic health using imperfect measures like unemployment rate is about like trying to manage your physical health using heart rate and body mass index figures. Can we do “good enough”? Only to a limited extent. We could stop eating garbage and get some exercise. But there isn’t some magic combination of vitamins and crystals that will stop cancer. Anyone who tells you otherwise is a) trying to sell you something and b) trying to convince themselves they’re in control of the uncontrollable.

In terms of macroeconomic policy, we should start by caring about fundamentals (i.e. long run economic development) and be skeptical of people promising to control the business cycle.

*And let’s face it, we aren’t likely to get decent macroeconomic policy (in terms of efficiency, timing, and appropriateness of policy to circumstances) out of Congress until there’s a serious cultural shift.

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