"The NAIRU is the level of unemployment at which inflation is stable. Ever since economists invented the concept people have poked fun at how difficult to measure and elusive the NAIRU appears to be, and these articles often end with the proclamation that it is time we ditched the concept. Even good journalists can do it. But few of these attempts to trash the NAIRU answer a very simple and obvious question - how else do we link the real economy to inflation?
One exception are those that attempt to suggest that all we need to effectively control the economy is a nominal anchor, like the money supply or the exchange rate. But to cut a long story short, attempts to put this into practice have never worked out too well. The most recent attempt has been the Euro: just adopt a common currency, and inflation in individual countries will be forced to follow the average. This didn’t prove to be true for either Germany or the periphery, with disastrous results.
The NAIRU is one of those economic concepts which is essential to understand the economy but is extremely difficult to measure. Let’s start with the reasons for difficulty. First, unemployment is not perfectly measured (with people giving up looking for work who start looking again when the economy grows strongly), and may not capture the idea it is meant to represent, which is excess supply or demand in the labour market. Second, it looks at only the labour market, whereas inflation may also have something to do with excess demand in the goods market. Third, even if neither of these problems existed, the way unemployment interacts with inflation is still not clear.
The way economists have thought about the relationship between unemployment and inflation over the last 50 years is the Phillips curve. That says that inflation depends on expected inflation and unemployment. The importance of expected inflation means that simply drawing unemployment against inflation will always produce a mess. I remember from one of the earlier editions of Mankiw’s textbook he had a lovely plot of this for the US, that contradicted what I just said: it displayed clear ‘Phillips curve loops’. But it was always messier for other countries and it got messier for the US once we had inflation targeting (as it should with rational expectations). See this post for details.
The ubiquity of the New Keynesian Phillips Curve (NKPC) in current macroeconomics should not fool anyone that we finally have the true model of inflation. Its frequency of use reflects the obsession with microfoundations methodology and the consequent downgrading of empirical analysis. We know that workers and employers don’t like nominal wage cuts, but that aversion is not in the NKPC. If monetary policy is stuck at the Zero Lower Bound the NKPC says that inflation should become rather volatile, but that did not appear to happen, a point John Cochrane has stressed.
I could go on and on, and write my own NAIRU bashing piece. But here is the rub. If we really think there is no relationship between unemployment and inflation, why on earth are we not trying to get unemployment below 4%? We know that the government could, by spending more, raise demand and reduce unemployment. And why would we ever raise interest rates above their lower bound?
I’ve been there, done that. While we should not be obsessed by the 1970s, we should not wipe it from our minds either. Then policy makers did in effect ditch the NAIRU, and we got uncomfortably high inflation. In 1980 in the US and UK policy changed and increased unemployment, and inflation fell. There is a relationship between inflation and unemployment, but it is just very difficult to pin down. For most macroeconomists, the concept of the NAIRU really just stands for that basic macroeconomic truth.
A more subtle critique of the NAIRU would be to acknowledge that truth, but say that because the relationship is difficult to measure, we should stop using unemployment as a guide to setting monetary policy. Let’s just focus on the objective, inflation, and move rates according to what actually happens to inflation. In other words forget forecasting, and let monetary policy operate like a thermostat, raising rates when inflation is above target and vice versa.
That could lead to large oscillations in inflation, but there is a more serious problem. This tends to be forgotten, but inflation is not the only goal of monetary policy. Take what is currently happening in the UK. Inflation is rising, and is expected to soon exceed its target, but the central bank has cut interest rates because it is more concerned about the impact of Brexit on the real economy. That shows quite clearly that policy makers in reality target some measure of the output gap as well as inflation. And they are quite right to, because why create a recession just to smooth inflation.
OK, so just target some weighted average of inflation and unemployment like a thermostat. But what level of unemployment? There is a danger that would always mean we would tolerate high inflation if unemployment is low. We know that is not a good idea, because inflation would just go on rising. So why not target the difference between unemployment and some level which is consistent with stable inflation. We could call that level X, but we should try to be more descriptive. Any suggestions?