Segmentation

Segmentation splits users, sessions or events into groups that share a property or a behavior, so a metric can be compared across those groups instead of read as one average.

A segment is a condition set evaluated against event history at query time: a user property such as city or plan, a behavior such as having purchased in the last 30 days, or an acquisition source. Segmentation is not the same operation as filtering. A filter removes part of the data from the view, while segmentation keeps the whole population and splits it so the groups sit side by side. The entity the condition applies to changes the answer: restricting sessions to mobile and restricting to users who ever used mobile return different numbers. The second common error is reading a gap between two segments as a cause, when the groups differ on a dozen other attributes at once, and small segments swing enough that a few points of difference mean nothing.