Did the iPhone 5 really overtake the Galaxy SIII in 18 days?

October 13, 2012, 2:40 PM UTC

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FORTUNE — Chitika Insights, a search-targeted advertising and research outfit that has made its share of mistakes in the past, generated a flurry of headlines Friday when it reported that Apple’s (AAPL) iPhone 5 Web usage had surpassed Samsung’s Galaxy SIII after less than three weeks on the market.

The feat seemed especially impressive because the Galaxy SIII had been on the market for more than four months and had actually outsold the iPhone in August — the first time since the dawn of the touchscreen smartphone era that any Apple competitor had done that.

But what Chitika left out of its Web usage report — which it said was based on an analysis of millions of mobile ad impressions from the two devices in the week of Oct. 3 to Oct. 9 — is that iOS always generates more than its share of ad impressions.

The fact is, Web usage is a terrible way to compare an Apple mobile device to one running on Google’s (GOOG) Android platform because the gap is consistently so large.

The chart above, drawn from NetApplications data, compares mobile operating system presence on the Web between November 2011 and September 2012. Over that time period, in which Android devices actually outsold Apple’s, iOS dominated the Web by a factor of more than three to one.

A better way to gauge the relative success of the iPhone 5 to the Galaxy SIII would be to compare the revenue and profits each generates. We’ll get a sense of how well the iPhone 5 did when Apple reports its fiscal Q4 earnings on Oct. 25. We’ll probably never get accurate data about the Galaxy SIII because Samsung stopped reporting mobile sales numbers more than a year ago.