When did he admit he was wrong?? Only after having his nose rubbed in his error many times, I'm sure.
Kellerman originally did the study for the CDC, and refused to subject his research to peer review. He was brought before a Senate subcommittee, ended up backing off a bit on his original numbers, and the CDC was defunded by a million bucks or so. As you can see though, the numbers live on in the minds and hearts of anti-rights zealots everywhere.
...but of course. Don't remember exactly when, but it seems like 2 or 3 years ago.