Answer
STAFF
Sam Wierema
19-Jan-2011 03:57:37
We get all our numbers directly through the Twitter API. Sometimes the numbers are incorrect, but unfortunately we can't do anything about this. It usually corrects itself within a few days though.
For a more technical answer on why Twitter reports the wrong numbers, please review the answer given by John Kalucki on Quora http://www.quora.com/Why-is-Twitter-having-problems-reporting-the-correct-number-of-tweets-a-user-has-made