I have a customer who complains his 'HTTP_REFERER' stats are not accurate. He is basing this on Urchin reports. Urchin shows a large percentage of visitors NOT having not been referred, however he expects that nearly all of his visitors are referred from other sites.
As I see it, there are two possibilities. One is that Urchin is getting bad data somehow from the logs. The other is that 'HTTP_REFERER' data is not being collected by Apache for some reason. Assuming the later, my theory is that modern antivirus / privacy software may be blocking Apache from learning the source of the referral.
I have work arounds for gathering stats by using GET parms for all inbound links, however that is a lot of trouble and doesn't integrate with Urchin, etc.
Does anyone have some insights or suggestions on the best way to collect reliable referral stats? Have any of you noticed the particular problem?