Absolutely. I should have added that to my post. A...

2007-12-27T15:28:00.000-06:00

Absolutely. I should have added that to my post. As I read your comment I started thinking that maybe excluding young and old individuals would do. That would be better than what the Treasury does, but not best: earnings still rise and fall over the life cycle, even considering people between the ages of 30 and 55, for instance.

One would have to track cohorts, as you say. With PSID data, for instance, you'd have to take 5-year cohorts, for example, in order to have a homogeneous group and still a decent sample size.

Thanks for leaving a comment!

You should also look at the fact that the Treasury...

2007-12-27T13:54:00.000-06:00

You should also look at the fact that the Treasury study didn't take into account age.

In other words, much of the move in income from first quintile to second quintile over the period in question simply reflects college students -- who are in the lowest quintile while in college -- graduating and starting careers.

Similarly, the drop in the income of the fourth quintile probably reflects people reaching retirement age, at which point their income drops off.

The only way to really study social mobility is to track a the quintiles of a generation, rather than simply quintiles over time. What matters is economic status among the peers of the same generation.

Comments on EconWeekly: Income mobility in the U.S.

Absolutely. I should have added that to my post. A...

You should also look at the fact that the Treasury...