Events per Session

Events per session is the average number of events occurring in a session: total events divided by the number of sessions in the period.

Events per session is a depth metric: it says how much a user does in a single visit, and its rise usually signals more engagement. But two things make it subtle. First, the number depends entirely on the definition of an event; if one day you add new micro-events to the code (logging every scroll, say), events per session jumps without any change in user behavior, so its trend only means something when the event definition held stable. Second, the average is highly sensitive to outliers; a few bot sessions or one session with thousands of events can inflate it, which is why it is better read beside the median or the distribution. The denominator must be sessions, not users; its sibling events-per-user divides the same numerator by users and shows different behavior.