什么是Session duration？
How long a visit lasted, measured from the first pageview to the last recorded activity in the session.
Session duration is the elapsed time from the start of a session to its last recorded activity. Averaged across sessions it becomes "average session duration," a common but frequently misread indicator of how long people stay.
The measurement has a structural blind spot: most tools compute duration from timestamps between hits, so a session with only one pageview and no further activity often records a duration of zero, even if the visitor read for ten minutes. Sites with high bounce rates therefore show misleadingly short average durations. Tools that send periodic engagement pings or track scroll depth get closer to real reading time. Two to three minutes is a reasonable average for content sites, but the median is usually far below the mean because a few long sessions drag the average up.
Treat duration as a supporting signal. A duration change with no change in conversions or page depth usually says more about your measurement than your audience.