This is a cool opensource tool, many thanks for sharing nate. User activation date is the most well-known cohort definition, but actually you can define a cohor

This is a cool opensource tool, many thanks for sharing nate. User activation date is the most well-known cohort definition, but actually you can define a cohort out of pretty much any data point you like, provided it makes sense to then run a longitudinal study on those cohorts. Marketing acquisition channel is another good one. If people are interested in finding out more about cohort analyses, we wrote a set of 7 articles which might be interesting: http://www.keplarllp.com/blog/2012/04/cohort-analyses-for-digital-businesses-an-overview http://www.keplarllp.com/blog/2012/04/cohort-analyses-for-di... And here's the hands-on tutorial for rolling your own cohort analyses in SQL with SnowPlow: http://snowplowanalytics.com/analytics/customer-analytics/cohort-analysis.html http://snowplowanalytics.com/analytics/customer-analytics/co...