Microsoft's decision late last year to switch on "silent" upgrades for Internet Explorer has moved some Windows users to newer versions, but has had little, if any, impact on the oldest editions, IE6 and IE7, according to usage statistics.
In December 2011, Microsoft announced it would start automatically upgrading IE so that users ran the newest version suitable for their copy of Windows.
Under the plan, Windows XP users still on IE6 or IE7 would be updated to IE8, while Windows Vista or Windows 7 users running IE7 or IE8 would be pushed to IE9.
Previously, Microsoft has always asked users for their permission before upgrading IE from one version to the next, even if Windows' automatic updates was enabled.
First to get the automatic treatment, Microsoft said, would be Australia and Brazil, both guinea pigs for the January 2012 debut. The program would then be gradually expanded to other markets.
Microsoft declined to disclose what other countries, if any, had had the auto-upgrade switched on.
But in Australia and Brazil, the move shuffled share among some editions of IE, according to data from StatCounter, an Irish web analytics company that publishes country-by-country usage share numbers for IE6, IE7, IE8 and IE9.
In both countries, IE9 jumped unexpectedly in February, the first full month after the auto-upgrade switch was thrown, while IE8 saw an almost-corresponding decline in share.
IE9 in Australia climbed 3.3% that month, a 23% increase, which was significantly greater than any spike of the previous 12 months. Meanwhile, IE8 slipped 2.8% in February.
The result in Brazil was eerily similar: IE9 jumped by 3.5% over the previous month and IE8 dropped by 3.1%.
There was some evidence that the auto-upgrade did impact IE7's share in Australia, since the browser's February decline was only a third that recorded for both January and March.
It's impossible to tell if, assuming some copies of IE7 were upgraded to IE8 or IE9, which operating system - Windows Vista or Windows XP - was affected: Both those editions can run IE7.
The theory that IE auto-upgrades primarily applied to Windows 7 and Vista users was bolstered by the shares XP owns in each of the two countries: In Australia, XP accounted for 19.5% of all operating systems used in February, while Brazil's XP share that month was double that at 37.7%.
If appreciable numbers of XP users had had their copies of IE upgraded, one would have expected to see Brazil's numbers for IE 6 and IE 7 show a larger variance from the norm than Australia. That just wasn't the case.
The shifts reported by StatCounter hint that IE's automatic upgrade program successfully moved some Windows 7 and Vista users from IE8 to IE9, but did little to migrate Windows XP users to a more modern browser, since IE6 and IE7 shares did not drop more than the usual.
Brazil, one of two countries where Microsoft has confirmed using IE auto-upgrade, showed a significant jump in IE9 share in February, but no unusual movement in the aging IE6 or IE7.