Browser usage reports: Lies, damn lies, and statistics

Chrome briefly overtook IE in the browser wars -- or did it? The devil's in the details of how StatCounter and Net Applications count users

With news so breathless it rated a press release, StatCounter announced yesterday that over the weekend David trounced Goliath, with Chrome taking 32.71 percent of global market share, trumping IE's lowly 32.5 percent. The crowds went wild, with bloggers dissecting the way Chrome usage goes up on the weekends, per StatCounter's numbers, while IE's goes down, only to reverse itself when the work week begins.

The people publicly crunching the numbers seem to forget that there's another firm with Web usage statistics, and Net Applications and its numbers show Chrome very gradually trending upward at around 19 percent, compared to IE's 53 percent.

StatCounter says IE has 33 percent; Net Applications says 53 percent. That's quite a difference. Who's right?

Not surprisingly, Microsoft sides with Net Applications -- to the point of posting a detailed explanation on the Exploring IE blog. There are three points where the companies differ: prerendering, geoweighting, and unique visitors.

Back in June 2011, Chrome started "prerendering" pages based on search strings typed into Google. As Google describes it, "Sometimes a site may be able to predict with reasonable accuracy which link the user is most likely to click on next -- for example, the 'next page' link in a multi-page news article. In those cases, it would be faster and better for the user if the browser could get a head start loading the next page so that when the user clicks the page is already well on its way to being loaded." Google.com uses prerendering for searches; it isn't at all clear what other sites use the Chrome-only prerendering technology.

Google has a "page visibility API" that tells Web stat packages when a page is being requested for prerendering.

In February, Net Applications stopped counting prerendered pages, claiming that "prerendering in February 2012 accounted for 4.3 percent of Chrome's daily unique visitors." Not surprisingly, the adjusted figures showed Chrome taking a big hit in February, with IE as the prime beneficiary.

StatCounter, on the other hand, states: "Looking at the trajectory of Chrome, however, it's apparent that this change did not have any significant impact on our stats at all. There is no bump or sudden jump in Chrome in our stats." And they give the data to prove their point: Chrome's growth has been steadily upward, with no resounding bump, prerendering or not. StatCounter counts page hits, regardless of the browser's willingness to show the pages to the user.

The second contentious issue is geoweighting. Neither Net Applications nor StatCounter have reporting sites that accurately reflect the number of Internet users around the world.

StatCounter says that in January it counted 18.1 billion hits -- but only 0.17 billion of those reported hits came from websites based in China. StatCounter just doesn't have that many tracking sites in Asia, even though there are somewhere around 50 percent more Internet users in China than in the United States.

Net Applications doesn't have enough data collection sites in China either, but it adjusts its numbers to account for how many Internet users are in each country. "Weighting by country nearly eliminates the effects of the geolocation of our client websites, and provides a much more accurate representation of internet usage market share." Net Applications began adjusting the numbers in August 2009.

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