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Difference between Median Visit Length and Average Visit Length

Products

Webtrends Analytics 9.x
Webtrends Analytics 8.x
Webtrends Analytics Legacy

Cause

“Median Visit Length” is the median of non-zero length visits in the log file. Half the visit lengths are longer than the median, and half are shorter. This number is often closer to the “typical” visit length than the average visit length. Numbers that are wildly atypical can skew the average, but will not skew the median so much.
“Average Visit Length” is a mathematical “average” of all non-zero length visits in the log file. For example, the following visitors visited the site:
User Visit Length
Bugs Bunny 00:15:01
Donald Duck 00:22:38
Mickey Mouse 01:09:42
Taz 00:24:09
Goofy 00:32:56
Snow White 00:00:35
Scooby Doo 00:05:34
Fred Flintstone 00:42:54
Road Runner 00:14:14
Pink Panther 01:10:20
Aladdin 24:00:00
The average time visited is 02:38:00. The median is 00:24:09. This is one example where the average can be skewed by extremely long or extremely short visits. In this case, the median is more significant for actual usage times on the web site than the average. For very popular web sites tracking users by cookies, the median may not be much different than the average.
Note: Average Time visited and Median Time visited terms are interchangeable with Average Session Length and Median Session Length.