Gauging Google's Bite

Google's "true market share" was closer to 70% when looking at traffic to a basket of Web sites, Skrenta added. "Let's look at search referral traffic the way a site owner would," he wrote, advocating his approach.

Looking at traffic with the lens of a site owner is important for investors as well, because most advertisers are, after all, also site owners. They may be as likely to turn to their own sites when assessing the merits of investing in ad campaigns on different search engines.

Most Wall Street analysts, meanwhile, continue to focus on the figures released by industry research firms when creating their estimates.

The rigorous methods and rich data generated by firms such as ComScore have many advantages over the kinds of back-of-the-envelope calculations used by Chowdhry -- who concedes that his sample size was far from scientific -- and Skrenta.

ComScore takes steps to ensure that its sample reflects the broader demographic of Web users, and transparency in browsing habits provides marketers with vital information, such as what types of products consumers are buying online.

Still, while the sophisticated and heavily publicized data by researchers such as ComScore, which releases figures to the press on a monthly basis, may be hard to miss, investors should keep the quick, crude calculations like Chowdhry's in mind as well.

The definition of what constitutes a better measure of market power is at the heart of the debate. And there, Chowdhry's "proof is in the pudding" approach provides valuable insights for investors as well.