Sunday, December 25, 2011

Is there an economist is the house? Casey Mulligan edition

After Christmas dinner, I did some web surfing and came across the following from Noah Smith:
Two posts back, I explained why the "Great Vacation" idea doesn't pass the smell test. If U.S. unemployment had been caused by a negative shock to labor supply, we should have expected to see an increase in real wages.

Casey Mulligan, one of the leading proponents of the Great Vacation story, responded on his blog:

A number of bloggers have recently discovered real wages as a labor market indicator. They are at least 3 years late to the party.

Three years ago I blogged about the effect of labor supply on real wages;

I noted how real wages had risen since 2007, and predicted that they would begin to decline in 2010.

I have continued to update this work, eg here, and here. The fact is that the real wage time series fits my recession narrative very well.*
Smith then pulls up a graph of real wages and uses it to argue that the data does not, in fact, fit Mulligan's narrative. It's definitely something you should check out, but right now there's something else I'd like you to take a look at. If you follow the link where Mulligan talks about blogging about the effect of labor supply on real wages, you get a column discussing the relationship between labor supply and productivity. This seems to be the relevant passage:

The second type of explanation is reduced labor supply.

Suppose, just for the moment, that people were less willing to work, with no change in the demand for their services. This means that employees would have to be more productive because they have to get by with fewer workers.

Of course, people have not suddenly become lazy, but the experiment gives similar results to the actual situation in which some employees face financial incentives that encourage them not to work and some employers face financial incentives not to create jobs.

Professor Douglas gave us a formula for determining how much output per work hour would increase as a result of a reduction in the aggregate supply of hours: For every percentage point that the labor supply declines, productivity would rise by 0.3 percentage points.

As mentioned earlier, in late 2008, labor hours were 4.7 percent below where trends from previous years would predict the number to be. According to Professor Douglas’s theory, this means productivity should rise 1.4 percent above its previous trend by the fourth quarter.

So let’s take a look at the numbers. Unlike in the severe recessions of the 1930s and early 1980s, productivity has been rising. Through the third quarter of 2008, productivity had risen six consecutive quarters, with an increase of 1.9 percent over the past three, or 0.7 percent above the trend for the previous 12 quarters.

Because productivity has been rising — almost as much as the Douglas formula predicts — the decreased employment is explained more by reductions in the supply of labor (the willingness of people to work) and less by the demand for labor (the number of workers that employers need to hire).
This way outside my field, so I could easily be missing the obvious here, but this post doesn't seem to support the claim that Mulligan was blogging on this question three years ago. That's not to say Mulligan's argument isn't valid or that it doesn't somehow imply his point about wages but if you're going to say "Three years ago I blogged about the effect of labor supply on real wages," you should probably mention wages in more than a passing way.

I can be sympathetic. Since I started blogging I've often recalled some prophetic observation I made in the past and started typing up a boastful post only to discover on review that I actually hadn't been that prophetic after all.

That's why I always reread old posts before I link to them; if I don't, someone else will.

* I had to remove a couple of reams of html formatting here. If I inadvertently removed something else. let me know.


  1. I liked this post from Noah Smith a lot, although I focused on a different issue. A lot of modern economics has slipped into issues of blame and attribution. Employment is high because people don't want to work and so it is the fault of the unemployed that they do not have jobs.

    Now, no narrative is ever pure and, in any complex society, this will be true of at least a few individuals. In the limit, we have the mentally ill to contend with.

    But the genius of Smith's piece was to point out that the evidence is in the opposite direction.

    But the fundamental issue, that conclusions have important consequences, poisons the whole field. We have the same issue with comparative effectiveness research -- when a lot of money, power, or status (and, to be frank, people's lives) ride on the answer, it is easy to find partisans on both sides.

  2. Good catch, Mark! I also noticed the absence of actual discussion of wages in Mulligan's paper, but gave him a pass because I'm sure he assumes that wages = labor productivity. In fact they do not, but I just decided to ignore his (intentional) oversight... ;-)