Assuming that Net Applications is right -- which outsiders might find hard to swallow -- the data showing a record fall of Windows XP, and for that matter the record increase of Windows 8, were in reality adjustments, not one-month real-world changes. In other words, Windows XP had been declining at a more rapid pace all along, while Windows 8 had been increasing faster than Net Applications had measured previously.
"Unfortunately, we can't go back and apply this change to historical data," said Vizzaccaro.
The one-off decline of Windows XP's user share also impacted other operating systems. Because Net Applications reports user shares as percentages of a whole, a drop in XP would require a corresponding increase elsewhere. That may have been the cause of the dramatic October boost to Windows 8's user share as it, too, was readjusted. It also meant that other OSes, such as Windows 7 and Apple's OS X, may have been under-reported previously.
There are oddities that remain in Net Applications' data, however, even after the company's explanation. For October, the firm pegged the user share of Windows NT at 1.64%, an inexplicable increase from 0.05% of September. Windows NT, a precursor to Windows 95, was first released in 1993.
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