Bentler - 2:21 pm on Jul 11, 2001 (gmt 0)

Invalidate is a strong word- I think weaken is more realistic. You can't know the absolute number of visitors or the actual time spent online, for a number of reasons including ISP & browser caching, the back button etc. But you can derive good comparative info about a site like customer preferences for certain topics, seasonal variation in usage of certain pages, relative amount of time spent on certain pages, etc. I also use log analysis to identify pages accessed from bookmarks, identify directories where favicon.ico was grabbed, identify and measure SE and other referrers, list most common errors, gauge browser usage, identify common keywords used to access the site from SE's, list common keywords to access pages from our internal SE, identify peak usage times, and other things.

This info is useful to reorganize a site to emphasize certain topics and at various times of year, improve weak content, design and language, improve site exposure of difficult to find but sought after pages, prioritize site repairs, target SE's with weak referrals, time announcements and news, and other activities that require priority setting based on a feedback loop. It also provides a decent measure, on average, of the general effectiveness of a site and the interest in it.

Caching should lop off peaks on relative page usage, but from my experience, there's always a correleation between most referred, most bookmarked pages and highest page usage. There's also always a correlation between the most compelling content and highest average time spent on a page-- despite caching and the back button that weakens absolute measurements, composite results from numerous visits provides very good information. From what I've seen personally.