I'm developing a simple stats page for my affiliates and I'm wondering the best way to figure out the number of unique users an affiliate has sent us. Obviously there is no way it's going to be 100% accurate or even close to it, but is there a general consensus on how I should count visitors? For example, the same IP address within 4 hours will count as 1 unique visitor. Or maybe only within 1 hour, etc. etc. Or should I dig deeper and also track it by the user agent, etc. Can anyone give me some rough guidelines? Thanks!
