

Analytics firm Chitika today released a report showing that by its metrics iOS has now surpassed OS X in overall web traffic share in the United States. Chitika's methodology involves an analysis of browser user agents for hundreds of millions of ad impressions across its expansive network.

To quantify this study, Chitika Insights analyzed several data sets composed of a series of US traffic taken from August 2011 to February 2012 out of the Chitika Ad Network (covering hundreds of millions of ad impressions). The user agents of individual impressions were then aggregated to determine relative overall share of the different operating systems.

Chitika's results show that iOS and OS X have seen their shares of web traffic quickly converge between September and December of last year, with the two platforms running neck-and-neck since that time.

iOS has been posting regular gains, and has experienced an overall growth of nearly 50%, whereas OS X has seen its market share decline by 25% since a high point in September. February marks the first point where a reversal in position can be seen in the respective operating systems. iOS passes Mac OS with 8.15% of all web traffic, whereas Mac OS only sees 7.96%.

Chitika theorizes that the decline in OS X share may be due to either Apple customers choosing to purchase iOS devices instead of Macs or simply a general increase in mobile usage that is overwhelming growth in traditional platforms such as OS X. Given Apple's continued record Mac sales over the past several quarters, the latter explanation seems to be the more likely one.

Chitika's results appear to be supported by worldwide data from Net Applications, which shows that desktop share outweighs mobile and tablet usage by a roughly 10:1 margin. With Apple holding only 6% of the desktop share but over 50% of the mobile and tablet share, iOS and OS X do appear to be fairly close in their shares of the overall market.