How many daily uniques does a site ranked 20,000 get? I know someone who gets 12,000 uniques a day and is ranked around 58,000, yet I have heard people say they have managed to get in the top 100,000 with as little as 100 uniques.
Alexa can only give you very very rough estimate and you can use it to check if the site is somewhat visited. You can not predict the UVs based on Alexa
eh, i believe alexa rankings start to get accurate as you start to rank higher (i.e. a lower ranking number).
In my opinion it's not that useful but it does at least allow you to compare traffic to other sites in the same niche. But you need to be aware of the following . . . Having the toolbar installed will artificially inflate your own figures if you visit your own site eg having it set as your homepage. That's how some people get their sites so high with so little traffic. The Alexa toolbar isn't currently available for FireFox but there is an extension available (SearchStatus, I think) that'll pull both the Google PR and the Alexa rank for every domain that you visit. I presume that Alexa counts a request for a domain as a vote for it so this will also skew the results. If you accept that the data that it's based on is flawed then it's useful-ish
Alexa is not providing accurate information. One should not dependent on this tool for user estimation.
it can not be due to the way they track it. If they give you a code to add to your site and then based on that to measure the popularity this is something different
Alexa Rankings are not accurate, however most of the sites in the top 100,000 are generally popular and high traffic websites. Sometimes sites with high Alexa rankings might actually be getting a considerable amount of traffic. But they are not to be relied on too much as the ranking can be manipulated by installing the Alexa toolbar on your browser and visiting your site daily.