If you knew the actual traffic stats (by, say, owning the site) for a site that Alexa has traffic data for, you could use that to calculate a scaling factor to

If you knew the actual traffic stats (by, say, owning the site) for a site that Alexa has traffic data for, you could use that to calculate a scaling factor to the Alexa data. That is, assuming that Alexa's toolbar users visit sites in the same distribution as the rest of the internet, which probably isn't true.