Source: CIRP

FORTUNE — When it reports on Mac sales in its retail stores, Apple AAPL likes to make the point — as Tim Cook did again last week — that roughly half of the Macs sold in Apple Stores are sold to customers who never owned a Mac before.

In a report issued Monday entitled “What Tim Cook Didn’t Say,” Consumer Intelligence Research Partners, a Chicago-based research firm, suggests that Cook told only half the story.

As the chart above indicates, Apple’s retail partners do an even better job converting Microsoft MSFT Windows users to the Mac platform.

According to the CIRP’s independent survey, 75% of the Macs sold at non-Apple stores last quarter went to customers whose prior computer was a PC. At the Apple Stores, only 48% were PC converts.

That makes sense. Customers who visit Apple Stores tend to be Apple users. That’s not necessarily true of customers shopping at, say, a Best Buy BBY or Walmart WMT .

As the report puts it: “The Apple Store is the ultimate manifestation of the Apple brand, but it is not the front door.”

It’s available here.