Ken's Blog
Alexa must be the most maligned, useful service online. Webmasters seem to enjoy dismissing it as "useless." They usually give their own sites as examples, as if a sample size of one means anything in the world of mathematics. Or they explain how it can be gamed, as if that totally invalidates this valuable tool.
In fact, when you do a proper study involving tens of thousands of sites, such as we do with Site Build It! sites, there is an excellent correlation between the number of visitors that a site receives and the Alexa traffic ranking.
And Geoffrey Mack, who writes the Alexa blog, showed a different kind of correlation between ranking and traffic in a post two days ago. His post focused on the tight correlation of traffic and Alexa ranking for two sites with excellent rankings (Top 1000) over a period of time.
While useful, it was a touch disingenuous. Any two sites can be chosen to prove a point. And top-ranking Alexa sites have, due to the volumes of traffic, less scatter (i.e., a better correlation.)
So let's get to the bottom of this. Alexa is a tremendously valuable tool, if you understand how it works, including the nature of its sampling and therefore its bias. With that under your belt, you will find true value in Alexa.