In preparation for some recent teaching, I went back to something that was a hot topic not long ago, and will be again if and when the crisis ends: the apparent lag of European productivity since 1995. One recent, seemingly authoritative study is van Ark et al; and I noticed something that gave me pause.

In their paper, van Ark etc. identify the service sector as the main source of America’s pullaway — which is the standard argument. Within services, roughly half they attribute to distribution — roughly speaking, the Wal-Mart effect. OK.

But the other half is a surge in US productivity in financial and business services, not matched in Europe. And all I can say is, whoa!

First of all, how do we even measure output of financial services? If I read this BEA paper correctly, we more or less use “checks cashed” — or, more broadly, the number of transactions undertaken. This may be the best we can do, but it’s a pretty weak measure of actual work done by the financial system.

And given recent events, are we even sure that the expansion of the financial system was doing anything productive at all?

In short, how much of the apparent US productivity miracle, a miracle not shared by Europe, was a statistical illusion created by our bloated finance industry?

Dean Baker has argued for some time that, properly measured, the productivity gap between America and Europe never happened. I’m becoming more sympathetic to his point of view.