Some stories are too juicy not to report, despite evidence that they're too good to be true. So it is with recent reports that Google's Chrome was briefly the most-often-used web browser, Microsoft says. And the reason is simple: The methodology used to measure Chrome's alleged recent success is inaccurate.

Online metrics firm StatCounter announced Wednesday that its data showed Chrome surpassing usage of Microsoft's Internet Explorer (IE) for a single day over the previous weekend. The suggestion is that workers home for the weekend turned to the browser they prefer—Chrome—and then went back to IE when they returned to work on Monday.

"While it is only one day, this is a milestone," StatCounter CEO Aodhan Cullen said, noting that Chrome accounted for 32.7 percent of web browser usage last Sunday, compared with 32.5 percent for IE. "At weekends, when the people are free to choose what browser to use, many of them are selecting Chrome."

Presumably tipped off that this report was coming, Microsoft on Sunday posted an analysis of the web-browser usage-share measurement, noting that StatCounter's metrics are seriously skewed because of pre-rendering and other factors. As a result, Microsoft claims, StatCounter can't be trusted as a reliable source of information.

"Net Applications and StatCounter both provide detailed browser usage data, [but] the two are very different when it comes to methodologies and results," Microsoft's Roger Capriotti wrote in a post to the firm's Exploring IE blog. "The overall share numbers they provide for each browser are significantly different ... raising the question of which data source is more reliable."

According to Microsoft, it is Net Applications that is more reliable. And the reason is simple, it says: StatCounter is measuring Chrome "pre-rendering," in which the browser preloads websites that it believes the user will want to visit next, in a bid to appear to work more quickly. But this pre-rendering skews the usage stats, making it appear as if Chrome is being used a lot more than it really is.

"Chrome is opening separate tabs that are invisible to the user," Capriotti explains. "A certain portion of these links will never be clicked and the user will never see them. Net Applications [removed] Chrome pre-rendered browsing traffic from its statistics, [becoming] the first company to adjust its data reports for websites Chrome users never visited. StatCounter simply publishes their data as they record it, without any adjustment for pre-rendering."

There are other factors, Microsoft says, including geoweighting, in which Net Applications more accurately accounts for the global population, and the measurement of actual users, not page views. "StatCounter only reports absolute page hits without any filtering," Capriotti continues. "Net Applications actually reports usage share based on unique visitors. It is this type of analysis that allows them to achieve more accurate representations of browsing habits and actual usage ."

Of course, few have reported Microsoft's stance, choosing instead to focus on the fanatical headlines and rote "IE is on the way down" storyline.