“The two leading high tech market research firms have done it again,” Philip Elmer-DeWitt reports for Fortune.

“They issued their preliminary PC sales estimates for the first calendar quarter of 2013 Wednesday, and while they agree that it represented either the worst quarterly decline on record (IDC) or the worst in a generation (Gartner) — thanks in large part to the disruption caused by the iPad and its imitators — they can’t seem to get their stories straight on the sales of Apple’s computers,” P.E.D. reports. “According to Gartner, Mac sales in the U.S. grew 7.4%. According to IDC, they fell 7.5%.”

P.E.D. reports, “We’ve seen the two firms get their Mac signals crossed before, but never this badly. In the summer of 2012, IDC had U.S. Mac sales falling 1.1% in the second quarter while Gartner had them growing 4.3% — a 5.4% gap. This time they disagree by nearly 15%.”

Read more in the full article here.

Related articles:
Gartner: PC Market posts 11.2 percent decline in Q113; Apple Mac sales up 7.4 percent in U.S. – April 10, 2013
IDC: PC shipments post the steepest decline ever in a single quarter, down 13.9% in Q113 – April 10, 2013