Discrepancy between webalizer and nettracker uniques

webalizer counts 2x nettracker uniques

[voltrader]

I was affected by the latest tweak to G's algorithm.

Webalizer uniques don't indicate this, but it's apparent by G's adsense impressions. NetTracker, on the other hand seems to indicate unique visits more along the lines of what I expect.

Webalizer "visits" are over 2x NetTracker unique visitors. Why is there such a large difference?

[dcrombie]

From the webalizer config file:

# Visits are determined by looking at the time of the current  
# request, and the time of the last request from the site. If  
# the time difference is greater than the VisitTimeout value, it  
# is considered a new visit, and visit totals are incremented.  
# Value is the number of seconds to timeout (default=1800=30min)

I'm not sure how NetTracker determines this but it sounds like it may be different.

[sullen]

Some ISPs (AOL is a prime example, but there are others) use proxy servers to access web pages, so one visitor will appear in the logs with a number of different IP addresses.

webalizer definitely didn't account for this last time I looked - it counted one AOL visit a number of times - but it may be that nettracker does.

[voltrader]

# Visits are determined by looking at the time of the current
# request, and the time of the last request from the site. If
# the time difference is greater than the VisitTimeout value, it
# is considered a new visit, and visit totals are incremented.
# Value is the number of seconds to timeout (default=1800=30min)

Thanks! Explains it.