Are public sector workers overcompensated? A month ago, I’d have said “probably”. Today I think we’ve found the smoking gun.

Here’s what I knew a month ago: Public-sector quit rates are roughly one-third of their private-sector counterparts. The obvious explanation is that public-sector jobs are generally too cushy to walk away from. It seems to me that it would be hard to account for that factor of three in any other way, though you can see some reasonable attempts in the comments here. (To be clear: I think that some of the factors in these comments can reasonably account for part of the difference in quit rates. I find it implausible that those factors are collectively substantial enough to account for a factor of three.)

A month ago, that was the best evidence on the table. Today, thanks to the protestors in Wisconsin, we’ve got something like proof positive.

Here’s why: If you cut the pay of an overpaid worker, he’ll generally scream bloody murder. After all, overpaid workers like to stay overpaid. But if you cut the pay of a non-overpaid worker, you haven’t really damaged him. He just quietly leaves and gets a job elsewhere. After all, the ability to find a comparable job elsewhere is pretty much the definition of not being overpaid.

Now how are the Wisconsin public workers reacting to projected pay and/or benefit cuts? As if the rug’s been pulled out from under them, that’s how. Every time a worker says “These cuts will cause me severe pain”, that worker is saying, in effect, “I can’t get anyone else to pay me at the level I’m accustomed to”, or, in briefer words, “I am overpaid!”.

So yes, they’re overpaid. And the louder they get, the surer you can be.