Alexa was starting displaying rankings in 1998 to show how popular are a site was. Their main rankings results was based on usage of Alexa Toolbar. And thats believed not really accurate as the results would be only relied on users visit who use Alexa Toolbar on their browsers. Alexa has listened to users suggestions and realized this has to be fixed, Alexa has announced its major changes on its rankings algorithm.
In this updates, Alexa said the new rankings is more accurate as it is aggregated form multiple sources to give better indication of website popularity.
Your ranking wasn't wrong before, but it was different. Alexa toolbar users' interests and surfing habits could differ from those of the general population in a number of ways, and we described some of those possible differences on our website. While the vast majority of sites' rankings were unaffected by such differences, we've worked hard on our new ranking system to adjust for situations in which they could matter.
The new rankings should better reflect the interests and surfing habits of the broader population of Web users.
We believe that our new rankings system is much closer to what you asked for. We now aggregate data from multiple sources to give you a better indication of website popularity among the entire population of Internet users.Well, though they don't clearly which sources they relied upon, things are still interesting to follow. Alexa graph are now showing 9 month historic statistic only, instead of 5 years and they still keep recalculating this historic data.
We are recalculating historic traffic data and will continue to add it over the coming weeks. We apologize for the inconvenience, but should have several years of data back on line shortly.
It may be definitely a good news for those who got Alexa rankings increase, but not me. Mine is dropped *sigh*. Though I really understand the causes. Well April is a month full of surprises.