Tom Maguire at Just one Minute:

Patrick Ruffini identified an intriguing puzzle that leads Sitemeter to inflate traffic statistics for high-traffic sites.

Briefly, Sitemeter claims that each unique visiting IP address is tracked for half an hour.  But what Patrick deduced is that Sitemeter has a second, hidden constraint – its Basic service only stores the last 100 visitors.  On a low traffic site, that constraint means little.  However, the Daily Kos draws about 30,000 visitors per hour during prime time, which is roughly one hundred visitors every twelve seconds.

So, if Patrick is right, if I go to the Kos site I will be recorded as a unique visitor; if I then hit a second Kos page twenty seconds later I will be recorded as another unique visitor, despite Sitemeter’s protestations about a half-hour rule.  Due to the 100 visitor hidden constraint, Sitemeter will correctly record page views but overstate unique visitors.

Yeah, well, that isn’t the half of it, despite the idea that Tom does his own testing on the issue.

For quite some time now, the numbers being collected by Sitemeter,  are nowhere near this web sites internal trackers, in terms of unique visitors, page hits, and so on.

Normally, I wouldn’t complain very much.  but the fact of the matter is  just about everything to do with blog status is tied to Sitemeter numbers, including TTLB.  If these are inaccurate… and I have good reason to think they are….