Logfile analysis


Quantcast screen
ABOVE: A Quantcast page showing "Quantified" Web traffic at Europe for Visitors. (Click here for the actual page at Quantcast.com.) 

by Durant Imboden, Europe for Visitors

Quantcast is a Web-analytics service that offers public access to traffic and demographic data for millions of Web sites. It collects traffic data in two ways:

  • By tracking Web usage through code snippets on pages served by publishers who have signed up for Quantcast's free Quantified Publisher Program. This "client-side" tracking method is similar to the one used by Google Analytics.
  • By monitoring the browsing of a Web  "panel," or sample group, in the United States. (Usage data is supplied by Internet Service Providers and advertisers.) The resulting data provides estimates of U.S. traffic for "non-Quantified" publishers.

A panel is also used to obtain U.S. demographic data to help prospective advertisers (or anyone who's curious) learn more about Web sites' audiences. Here's a sample demographics chart--updated weekly by Quantcast--for our site, Europeforvisitors.com:

How reliable are Quantcast's traffic and demographic figures? 

  • For "Quantified" publishers, Quantcast appears to underreport visitor numbers slightly in comparison to Google Analytics, but its numbers aren't totally out of whack. Quantcast's "Quantified" methodology has been accredited by the Media Research Council, a U.S. organization that serves the advertising industry.
  • For non-Quantified publishers, Quantcast's numbers are questionable, and the numbers (called "estimates") are for U.S. traffic only.

The reliability of Quantcast's demographic data is less of an issue, because all demographic studies are (by nature) survey-based. 

My advice:

Once you have enough traffic to show up in Quantcast's U.S. traffic estimates, you might as well sign up for the "Quantified Publisher Program" and benefit from the insights that it provides. Registration is free, and it's better to have prospective advertisers or PR people see real data about your site instead of unreliable estimates.

Next article: "Alexa"


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