I know of two more tools for analyzing web site traffic - Google Analytics and Alexa. With Google Analytics, the site owner puts a script (provided by Google) in each web page to be analyzed. The script sends Google the visitors data for analysis (hence "Thinking outside the box"). Alexa takes an "Outside looking in" approach - PC users install the Alexa Toolbar, which collects data on their browsing habits. Alexa then uses this data to estimate the number of users that go to each site.
Google Analytics offers a granular view of site traffic, how/where it originates (searches, referrals or direct visits). Reports show what visitors are doing when they come to the site. All a site owner needs to do is open a Google account and paste the script in the pages (I included the script in PmWiki's CSS file's header section). Google Analytics offers free, powerful reporting features, which can be accessed on line, or emailed at preset times to selected individuals. This service is a win-win to both user and Google. I get an incredible amount of data on my users without spending a cent, and Google gets first hand user data, which they can use for world domination.
Alexa approach is to track where people who have installed the Alexa tool bar application are surfing. From this data, Alexa can tell how visits to your site rank relative to other sites, or compare the popularity of two sites over a period of time. The validity of the analysis is based on the assumption that their traffic data can be extended to the community at large. This assumption is almost surely wrong - Alexa users are a group whose characteristics are almost certainly different from the Internet users universe. For one, Alexa's site is in English, so o English speakers likely weigh heavily in the traffic analysis. Users with privacy concerns, or under repressive regimes, may be less likely to send their traffic to Alexa for analysis, etc. As in every statistical analysis, inference accuracy drops when less data is available, i.e. when a site is not very popular. To Alexa's credit, they openly recognize this fact. Graphical information is only available for sites in the top 100,000 sites.
Still, Alexa is a nice tool for a 'quick and dirty' traffic comparison between sites. For example, I find that words2u.net has a traffic rank of 7,737,112, which is up 3,297,142 places from 3 months ago. Alexa connects to the Wayback Machine archives to provide snapshots of web sites in past time. If you do not believe in reincarnation, a visit to that site might change your mind, especially if you happen on a site that changed ownership. Web site owners can check their ranking by pointing their browser to www.alexa.com/data/details/traffic_details/web.site.name.
