If you compare AWStats results with an other log file analyzer, you will found some differences, sometimes very important. In fact, all analyzer (even AWStats) make "over reporting" because of the problem of proxy-servers and robots. However AWStats is one the most accurate and its "over reporting" is very low where all other analyzers, even the most famous, have a very high error rate (10% to 2x more than reality).
This is the most important reasons why you will find differences:
- Some dynamic pages generated by CGI programs are not counted by some analyzer (ie Webalizer) like a "Page" (but only like a "Hit") if CGI prog has not a .cgi extension, so they are not included correctly in their statistics. AWStats does not make this error and all CGI pages are pages.
- AWStats is the alone analyzer (that i know for the moment) able to detect robots visits. All other analyzers think it's a human visitor. This error make them to report more visits and visitors than reality. This does not happen with AWStats. When it tells "1 visitor", it means "1 human visitor". All robots hits are reported in the "Robots/Spiders visitors" chart.
- A lot of analyzer (ie webalizer) use the "Hits" to count visitors. This is not a good way of working : Some visitors use a lot of proxy servers to surf (ie: AOL users), this means it's possible that several hosts (with several IP addresses) are used to reach your site for only one visitor (ie: one proxy server download the page and 2 other servers download all images). Because of this, if stats of unique visitors are made on "hits", 3 users are reported but it's wrong. So AWStats, like HitBox, considers only HTML "Pages" to count unique visitors. This decrease the error, not completely, because it's always possible that a proxy server download one HTML frame and another one download another frame, but this make the over-reporting of unique visitors less important.
There is also differences in log analyzers databases and algorithms that make details of results less or more accurate:
- AWStats has a larger browser, os and search engine database, so reports concerning this are more accurate.
- AWStats has url syntax rules to find keywords or keyphrases used to find your site, but AWStats has also an algorithm to detect keywords of unknown search engines with unknown url syntax rule.
About the Author:
Peter Ruijter is a programmer living in Vianen, The Netherlands
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Published on January 11, 2007 in 
Dear Peter,
I read your review on AwStats. You stated that Awstats counts all CGI pages are pages .
I experienced it the other way around.
Maybe you have an answer to my question in the AwStats-Forum?
http://sourceforge.net/forum/forum.php?thread_id=1745399&forum_id=43428
Hi André,
In your question in the sourceforge forum, you complained that AWstats ignored URL query information.
URLWithQuery will to the job for you, when you set this option to 1 in your awstats configuration file. Your query string information will now be visible. By default this option will be disabled, so that's the reason why AWStats give you those results by default.
Warning, when set to 1, memory required to run AWStats is dramatically increased if you have a lot of changing URLs (for example URLs with a random id inside). Such web sites should not set this option to 1 or use seriously the parameter URLWithQueryWithoutFollowingParameters. More informational about this you'll find at http://awstats.sourceforge.net/docs/awstats_config.html#URLWithQueryWithOnlyFollowingParametes.