How many people have lost their jobs?

According to Barack Obama, 600 thousand Americans have lost their jobs since January. Actually, he's wrong: something like 20 million Americans have lost their jobs since January. It's just that most of them found new jobs. Probably the new jobs generally weren't as good as the ones they lost. And almost certainly, more than 600 thousand of them were unable to find new jobs, because many of the new jobs created were filled by new entrants to the labor force or by people who were already unemployed when the year began.

Like almost everyone else I've ever heard, Senator Obama is making the mistake of using a net job loss figure with language that, if taken in its plain sense, clearly implies he is talking about gross job loss. And it seems to me that gross job loss is the appropriate concept: losing your job is a pretty serious bummer, even if you are able to find a new one after a few months.

There has been a lot of talk about Senator McCain and how he has been saying things that aren't true in order benefit himself politically. It turns out that Senator Obama is also (obviously unintentionally) saying things that aren't true, but in this case they benefit his opponent.