Comscore undercounts Firefox


5. Firefox and Safari. We knew that Comscore’s toolbar did not work on Safari, and therefore did not count the typically sophisticated users of the Apple Mac internet browser. But I hadn’t realized how much Comscore undercounted usage of Firefox. The Mozilla browser is used by about 15% of the US internet population; Firefox devotees account for only 7% of Comscore’s panel, according to a publishing exec who has spoken recently with the firm.
So, what does that mean? Well, a site viewed, hypothetically, only by Safari users, would show as having no audience at all. A site with only Firefox fans would register with about half the audience it should. A normal tech site? The audience for Lifehacker, Gawker Media’s software and productivity title, is about 60% Firefox, 5% Safari, and 30% other. Assuming Comscore doesn’t take account of its undersampling of geek browsers, that factor alone would cut Lifehacker’s measured audience by 33%. And that’s compounded by the more general problems with Comscore that and other big internet publishers are complaining about.

STATS: How Comscore kneecaps Silicon Valley startups – Valleywag