For a few years now, I have been tracking Mac market share, using Net Applications’ market share reports. From the beginning, I tagged the measure as unreliable in terms of representing actual market share, but found it acceptable as a way of measuring relative growth. Kind of like Rasmussen polls–you know they’re slanted to the right, but if they maintain the same methodology, they can be a relatively accurate measure of change over time.

Well, Rasmussen recently changed their methodology and so made it look like Obama tanked in the polls–much to the delight of their right-wing audience–when in fact there has not been too much change.

And wouldn’t you know it, at right about the same time, Net Applications changed their methodology as well, giving greater weight to foreign web surfers, which gives greater weight to Windows and much less weight to Macs. Previously teetering at 10%, the Mac OS is now rated at less than 5%. This may be more reflective of a worldwide market share, but the whole point of using Net Application’s data was it’s relative worth; we knew all along that the way it gathered data already favored Windows users.

Had NA kept both methodologies, that would be of some use, but now, I’ll have to throw all the data from the past few years out the window. Thanks for nothing.