It's fairly common practice to define a unique user by a 1-to-1 hash of IP + User Agent. But not all unique users have a unique IP + User Agent combination. Thus: collisions - events misattributed to users who did not fire those events.This is especially problematic when trying to track unique users who use similar machines and settings all under the same roof of a large organization like a school or enterprise.My question is: What is the global background probability of IP + User Agent concurrency at any given time?I assume the rate is different for different times of day and regions. But I'm curious what the standard is.
What percent of all active IP + User Agent combinations are not unique?
tracking;ip address;user agent