On 09:15:47 24 June 2005 helruna wrote:

          some hints on how to deal with different readings 
          from their experience.

"Don't try" is my advice.
Web analytics tools capture data in multiple ways. They cleanse that data in multiple ways. They report out that data in multiple ways. While they are consistent, they are never in agreement. The business side of the house demands precise numbers. You'll have to show them how tracking trends is more important than knowing specifics to three decimal points.

Hi there

Is that 2 different sets of log files or 2 different web log analysis tools? Or both?

The log files, if generated by the same web server using the same configuration, should generate consistent log files. I say 'consistent' because they may have a lot of redundant information in them which needs stripping out of any reporting, but at least you can compare like with like. 

If they are not the same web server, or the settings have changed, then this could be the root of your problem. For example, have you moved from CLF (common log file format) to ECLF (Extended common log file format)? Have you kept your session time out setting the same on the web server (usually 30 mins)? These things, and others, could make a big difference to what results will get spit out of standard like-for-like analysis and reporting. 

If you're sure that the logs files are consistent, then the most likely cause of difference in figures between 2 analysis tools is the way they are configured. Again, check the session timeout assumed. Most likely, though, it will be an inconsistency in what is being filtered out or not. Typically, around 15% of site traffic might be non-human and needs to be filtererd out. If you've got frames, or automated agents pinging your site every 10seconds, or a range of other things, your stats could be skewed a lot if your exclusions are not thorough and consistent. 

As Jim says, you should focus on trends and shouldn't worry about small inconsistencies. However, very large inconsistencies are most likely down to one or other of the reasons I mention above. 

We've got multiple (3) web analytics tools running on our site, using page tags rather than web server log file analysis, and the margins of difference between them is actually so slight as to be not worth worrying about.

Ashley

p.s. in answer to your question about free tools out there, perhaps the most common are:

Statcounter - for free page tag / ASP tool
Analog - for free log file analysis

There are downsides to these free tools and with prices coming right down on professional web analytics solutions (e.g. to around £100 a month) then it might well be worth looking at these too.

Plenty of info on these tools in our Web Analytics Buyers Guide 2005

Ashley