After using the same system for the last 10 years, Alexa has changed the way they rank website traffic. They have used the Alexa Toolbar as their basis of traffic rankings. The problem with this system is that it relied on users who downloaded the Alexa toolbar. Webmasters had more incentive than the average user to use the toolbar, resulting in a bit of skewed results.

Alexa says that the new rankings are the results of a “new and improved algorithm”. They also say that “the new rankings should better reflect the interests and surfing habits of the broader population of Web users”. They say that the new rankings are based on more sources of data but they do not provide these sources. Here is a link to the Alexa announcement.

An interesting effect of the change is the history. They state that that they are”recalculating historic traffic data” and that they will continued it over the coming weeks”. They “should have several years of data back on line shortly”. I’m am not sure how they can retroactively calculate this data unless they have have collecting it over many years. Maybe the purchased it from someone like Google.

I’m sure we will here more in the near future.