According to StatCounter, its data is based on the analysis of four billion pageloads per month among StatCounter's two million members.

Compared to some of its competitors, however, some of StatCounter's data points seemed a bit off to us. StatCounter, for example, saw Google's U.S. market-share in January at over 80% (and down from a high of close to 85% last fall), while Hitwise reported 72% for January. StatCounter also sees Mac OSX as hovering around 4% worldwide, while Net Applications reports it at 9.6%. RWW readers, by the way, skew more heavily towards the Mac than the mainstream, as Google Analytics tells us that about 20% of you use Apple's OS.

For mobile operating systems, StatCounter reports that the iPhone is in a neck-and-neck race with the SymbianOS (about 35% each), while AdMob's global stats (PDF) saw Symbian as leading the race with 44% (32% for the iPhone).

Source: StatCounter Global Stats

One nice feature of StatCounter's tool is that it is updated 5 times a day. However, while this would be great if StatCounter was showing us data from specific sites, these frequent updates almost seem like overkill when it comes to the broad categories that the company currently tracks.

Given that there is no universal standard for how to measure these statistics, any of these numbers from any service have to be taken with a grain of salt. StatCounter gets its data from all the sites that use the service, and chances are that the types of sites where StatCounter is installed on inevitably skew the data in one way or another.

Overall, StatCounter is providing a valuable service with this new tool, but users will still have to compare the information from Global Stats with data from other services and draw their own conclusions about the validity of that data.