AppleInsider reported on how Apple’s double digit growth contradicts estimates by IDC and Gartner that Mac sales fell.

Earlier this month, IDC (above) reported that Apple’s U.S. Mac unit sales in Q2 (Apple’s fiscal Q3, the quarter ending in June) fell by 1.7 percent, while Gartner (below) reported a drop in Mac unit sales of 1.3 percent.

Globally, Apple reported that Mac sales jumped from 3.75 million to 4.41 million year-over-year for its fiscal Q3, a unit increase of 18 percent and a new June quarter record.

18 percent increase is a big difference compared to a drop of 1.7 percent.

Shocking? Not if you’re aware of how these analysts portray data:

IDC, Gartner and Strategy Analytics have a long history of presenting carefully contrived data in press releases clearly designed to flatter their clients and denigrate their clients’ competitors, with Apple being a common target.

In addition to excluding iPads from their PC sales (while counting Windows tablets and including every other new form of PC device), IDC has also (like Strategy Analytics) radically revised its tablet figures after the fact, inventing, for example, Samsung tablet shipments that retroactively disappeared in the next year’s figures.

At the same time, IDC inflated its year ago estimates of the number of tablets attributed to unnamed “other” vendors by nearly ten million units, creating unflattering market share numbers for Apple in 2012, followed by unflattering market share growth figures for Apple in 2013, all coaxed from shifting numbers presented without any verifiable source. Apart from Apple, no other significant tablet vendor reports its unit sales.

IDC has also obscured the reality of Apple’s iPad sales by comparing them to kids tablets and toys, in order to water down Apple’s “market share” and imply that iPads are falling out of fashion—while distracting all attention away from the fact that nobody is selling premium tablets in volumes like Apple with margins like Apple.

Earlier this year, IDC was found to have added Windows 8.1 “2 in 1” PC notebooks into its reports of tablet shipments, another effort to portray Apple’s “share” of the “market” as diminishing, and a direct reversal of IDC’s staunch policy of not counting iPads as PCs, ostensibly because they are completely different product categories with no perceivable market impact on each other.

A former IDC researcher spoke to Fortune:

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.