As previously complained about, Alexa is not the most effective measured form of traffic measurement. But it’s global, and free, so that makes it more difficult to complain about.
this has all changed with the release of their new method of calculation,; according to their press release; “Your ranking wasn’t wrong before, but it was different.” . so I took a look at our “different” ranking, and it seems like it hasn’t had a considerable change, I checked a couple of weeks ago and we were on about 500 and this morning we were on 530. so it seems the new and improved ranking is just as effective (at least for our site) than the old site. i know there have been some pretty seismic changes if you read the comments below the techcrunch post