Audience Cohort

An audience cohort is a set of users sharing a common trait — for example everyone who first arrived in a given week — that is then followed as a single unit over time.

A cohort differs from a simple filter: a filter is a snapshot of whoever meets a condition right now, while a cohort is a fixed group locked by one event or time and then tracked forward to watch that same group behave. Its most common form is the acquisition cohort, which buckets users by the time of first entry, because that bucketing answers whether recent arrivals stick as well as older ones did. The main trap is confusing a cohort with a segment; a segment can gain and lose members, whereas a cohort stops recruiting once it is closed. For a web audience, the cohort is the basis of every retention analysis and every comparison of arrival generations, otherwise total-user growth hides a decline in loyalty.