Revised data from a prominent Web metrics company dropped Apple under the 5 per cent market-share mark, about half what the same firm said Macs enjoyed just two months ago.
According to data released Saturday by Net Applications, Apple's Mac OS X accounted for 4.9 per cent of the total global market share in July, up from 4.7 per cent the month before, but off significantly from May's 9.8 per cent.
The dramatic drop was due to a change in the California company's methodology, which now weights OS usage by the estimated size of each country's Internet population. According to Net Applications, countries such as China, Brazil and India were underrepresented in its previous calculations, while others, like the U.S., were over-represented in its unique visitor tallies.
"Some major Internet markets were not as well-represented as they should have been," said Vince Vizzaccaro, Net Applications executive vice president of marketing, explaining the change. "China was one of those major markets, and one of the driving forces in Internet growth."
The result, he said, was that Net Applications' data leaned too heavily toward English-language site. "That's why the Apple numbers took a big hit," he said, noting that Apple's sales strength is also in English-speaking markets. "We had a strong Apple bias."
Net Applications measures operating system usage by tracking the machines that surf to the 40,000 sites it monitors for clients, which results in a data pool of about 160 million unique visitors per month.
But although Apple's share plummeted, Vizzaccaro stood by his company's data. "The trends are accurate," he argued. "It is a big change, but it's a more accurate portrayal of the Internet."
Apple's "loss" was Microsoft's gain: Net Applications pegged Windows total usage share for July as 93 per cent under the new way of counting clicks; using the old methodology, Windows accounted for 87.8 per cent of the OS market in May.
"Windows' increase is best attributed to Apple's lower numbers," said Vizzaccaro.
As Vizzaccaro said, however, earlier trends remained intact. In the new tallies, Windows slipped 0.4 of a percentage point in the last 90 days while the Mac climbed by 0.2 of a percentage point during the same period.
Net Applications also recorded the onward and upward march of Apple's iPhone and iPod Touch, which reached a total usage share of 0.36 per cent during July. In the two months since Apple rolled out the new iPhone 3GS -- and revamped the smartphone's and Touch's OS to Version 3.0 -- the two devices have surged by 0.06 of a percentage point, representing a 20 per cent share increase.
Discarding the old data also put a new spin on the OS share for each version of Windows. By weighting the numbers from countries like China, Net Applications boosted the market share of the older Windows XP -- 72.9 per cent in July using the new calculations, up from 61.5 per cent in May under the old count -- and reduced the share of Vista. "That makes sense," said Vizzaccaro, "because now we're giving more weight to countries that are behind, technology-wise."
Net Applications' new method put Vista share at just 17.9 per cent for July, compared to 24.4 per cent in May. (Net Applications applied the new methodology retroactively to its OS numbers so that, in the revised data, Vista's May share was 17.4 per cent.)
But the general trends within Windows remained the same as before. Windows XP slipped 1.5 percentage points in the last three months, for example, while Vista increased its share by 0.9 of a point. Windows 7, meanwhile, continued to grow its share, ending July at 0.9 per cent, up from June's 0.75 per cent and May's 0.6 per cent. Although Windows 7 has not been officially released, Microsoft has seeded millions of copies of a January beta and an early-May release candidate to the public.
At the same time, the ancient Windows 2000, which drops off Microsoft's support list in July 2010, fell under the 1 per cent bar for the first time, ending July at just 0.97 per cent.
Vizzaccaro also responded to critics who called the change in methodology "wrenching" while wondering if Net Applications' data could be trusted after the switch. "I think that's a bit of an overreaction," said Vizzaccaro. "Unless you measure the entire Internet, which is clearly impossible, any data will have some measure of error to it, and every usage share [number] will be an estimate to some degree."
Net Applications explained more about its methodology change on its Web site; the current operating system share data is also available.