From AppleInsider:

Apple reported “strong double digit growth” in its Mac sales in the U.S., directly contradicting the earlier estimates published by IDC and Gartner that stated Apple’s U.S. Mac sales fell year-over-year in the June quarter and calling into question the legitimacy of market estimates that the tech media uncritically presents as factual.

Writing for Fortune, Philip Elmer-DeWitt shines some light on how those “estimates” are made (or made up): (via The Loop)

“So, the mantra became, preserve the growth rates; to hell with the actual numbers. Even the growth rates are fiction. The fudge is in the ‘others’ category, which is used as a plug to make the numbers work out. In fairness, we did do survey work, calling around, and attending white box conferences and venues to try to get a feel for that market, but in the end, the process was political. I used to tell customers which parts of the data they could trust, essentially the major vendors by form factor and region. The rest was garbage.”