Chrome climbed by two-tenths of a percentage point -- off the seven-tenths of a point average between November 2010 and January 2011 -- to close the month at 10.9%, a new record for the browser. Safari gained a statistically-insignificant six-hundredths of a point, less than a fifth of its three-month average, to end February at 6.4%.
But while Vizzaccaro said he couldn't define the accounting change's impact -- Net Applications did not run the numbers using the old weighting scale -- he wasn't ready to credit all of IE's jump to the new CIA numbers.
"IE8 and IE9 both increased, and I don't think you can attribute those gains to China," said Vizzaccaro today. "In China, IE6 remains the dominate browser."
According to Net Applications, IE8 picked up seven-tenths of a percentage point, on par with the November-January average, to grab 35% of the browser usage share. IE9, meanwhile, edged up slightly more than its three-month average to end with a 0.6% share.
IE7 and IE6 usage both dropped during February, but at amounts less than usual. The nearly 10-year-old IE6, for instance, fell just one-tenth of a point last month using the new CIA data; in the preceding three months, it averaged a drop of 1.1 points each month.
The relatively small decline by IE6 seemed to back up Vizzaccaro's point that the browser is preferred in China.
In a blog post, Roger Capriotti, the director of IE's product marketing, acknowledged that the weighting change played a part in IE's climb.
He also defended what he said were clear gains by IE on Windows, the only platform on which IE runs.
"When adjusted using the older weighting, IE8 and 9 actually show even stronger growth on Windows: up 1.31 [percentage points] (versus 1.13 [points] using the new February weighting), or over three times Chrome's 0.42 [point] growth [on Windows]," said Capriotti. "We continue to measure our share progress relative to our addressable base, and in this case our addressable base is Windows."
Unlike Firefox, Chrome, Safari and Opera, IE only runs on Windows; all the others also run on Mac OS X, while Firefox, Chrome and Opera also have Linux editions.
Net Applications calculates browser usage share from data acquired from the 160 million unique visitors who browse approximately 40,000 Web sites it monitors for clients. The company's February browser data is available on its site.
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