Microsoft's claim that Internet Explorer 8 (IE8) and IE9 beat the usage share gains posted by Chrome last month don't hold up, according to the data the company cited Monday.

But the matter may be moot: Overall, IE again lost ground to Google Chrome and Apple's Safari in the battle for browser hearts and minds.

In a post to a company blog, Ryan Gavin, a senior director on the IE team, said that IE8 and IE9 boosted their combined global usage shares by 0.45 of a percentage point, and compared that to what he called Chrome's increase of just 0.19 of a percentage point.

"Our latest browser offerings saw a 0.45% increase in market share this month worldwide..., [a] higher worldwide growth than Chrome's Stable and Beta channels," said Gavin. Gavin cited October browser usage share numbers published today by Net Applications.

To arrive at his conclusion, Gavin measured gains made during October by IE8 and IE9 against a mix of Chrome versions. Gavin calculated Chrome's increase of just 0.19 of a percentage point by comparing the combined share of Chrome 5, Chrome 6, Chrome 7 and Chrome 8 in September (7.69 points, Gavin said) against the total of Chrome 6, Chrome 7, Chrome 8 and Chrome 9 in October (7.88 points).

But by tossing Chrome 5, Gavin struck 0.27 percentage point from Google's total, skewing the comparison in IE's favor. If Chrome 5 is added to the mix, Google gained 0.46 percentage point, virtually the same as IE8 and IE9, during the month.

Microsoft did not immediately reply to questions about its claims, and why it did not include Chrome 5 in its comparison.

While Microsoft touted IE8 and IE9 increases, total IE share continued to slip. Microsoft's browser accounted for 59.3% of all browsers used worldwide during October, Net Applications said, down 0.4 of a percentage point from the month prior. The mark is another record low for IE, and the third month of declines in a row after a two month run of gains over the summer.

Chrome was the biggest beneficiary of IE's losses, ending October with an 8.5% share, an increase of nearly half a percentage point. Meanwhile, Apple's Safari raised its share by less than one tenth of a point to 5.3%. Both browsers posted record share results last month.

Mozilla's Firefox and Opera Software's Opera were both down last month after showing very minor gains in September.

Firefox ended October with a 22.8% share, down more than a tenth of a percentage point and at the lowest point since July 2009. Mozilla's open source browser remained the overwhelming number two browser, however, with a share more than two-and-a-half times larger than number three, Chrome.

Opera slipped a tenth of a percentage point to 2.3%.

Rival web measurement vendor StatCounter had different numbers for the five major browsers. Its tally had IE at a 49.2% share of all browsers used in October, while Firefox and Chrome owned shares of 31.2% and 12.4%, respectively.

StatCounter's trends were similar to Net Applications', however, in that the Irish analytics supplier had IE, Firefox and Safari on the decline and Chrome and Safari on the upswing.

Gavin also noted a jump in IE9's share. "We're pleased to see that in addition to 10 million downloads, 0.32% of customers worldwide and 1.46% of Windows 7 users are using Internet Explorer 9 as their daily browser," Gavin said, referring to Microsoft's recent announcement that more than 10 million copies of IE9's beta have been downloaded since the preview debuted in mid-September.

IE9 is on a pace similar to IE8's a full month after the release of that version's first general public beta in 2008. Meanwhile, Microsoft's IE8, the company's current production browser, lost ground last month by one calculation and gained by another.

Net Applications pegged IE8's share at 29.01% for October, off the 29.06% of the month before, for the first drop in the browser's history. But when the browser's compatibility mode is added in, IE8 ended October with 32.09%, up from September's 31.75%.

IE's compatibility mode lets users view websites designed for older browsers with the newer edition. IE9 also includes the feature.

Microsoft's older browsers, the 2001 IE6 and the 2006 IE7, continued their slow decline in October. According to Net Applications, IE6 accounted for 15% of all browser usage last month, off more than half a percentage point. IE7 fell by almost as much and for the first time in more than three years, dropped under the 10% mark.

IE6 is on Microsoft's hit list, the company has aggressively urged users to ditch the nine-year-old program, but its decline may be tough to maintain, according to a recent report from Gartner Research, which said that enterprises are having a hard time abandoning the browser because of web application compatibility issues with IE8 and IE9.

Browser usage share is important for more than just bragging rights: The more users run IE, for instance, the more they're likely to use Microsoft's Bing search engine, the default for IE. Other browser makers also benefit from a larger share because of their software's default search engine. Mozilla, for example, relies on its search deal with Google for the bulk of its revenues.

Net Applications calculates usage share from data acquired from the 160 million unique visitors who browse the 40,000 websites it monitors for clients. The firm's October browser usage share data is available on its site.