Sam Roberts writes,
In 1984, according to the Social Security Administration, nearly 3.4 million Smiths lived in the United States. In 1990, the census counted 2.5 million. By 2000, the Smith population had declined to fewer than 2.4 million.
Where did all the Smiths go from 1984 to 1990? I can believe it flatlined after 1990, but it’s hard to believe that the count could have changed so much in 6 years.
Perhaps it’s the difference between the SSA and Census methods of counting?
Great blog. The quality is high, the topics interesting, and the honesty (willingness to be critical about the ideas of other people, and to express uncertainty) extraordinary compared to other academic blogs in this space. Although it may be costing you some audience, I really like that you don't appeal to lower denominators, by constantly signalling libertarian, liberal, or conservative, writing us vs. them type posts, or doing other things that I think have brought greater exposure to blogs like Robin Hansen's, Tyler Cowen's, and Arnold King's at the expense of a more enlightening environment.
In my opinion you're the mindhacks of statistics blog, which I mean as a great compliment.
Perhaps related: In 1987, the IRS began requiring that dependents have social security numbers on tax returns. Seven million children disappeared. (Described in Freakonomics)
http://origin.observer.com/node/50806
The simplest explanation is a typo. Change that Social Security estimate from 3.4 to 2.4 and the problem disappears.
I think ZBicyclist is correct. A less plausible scenario is that SSA's methodology produces wildly different results than the census.
The decline of Smiths from 1990 to 2000 is surprising enough.
Correct answer.