The answer is cohort. This is a gathering of subjects who share a characterizing trademark (ordinarily subjects who encountered a typical occasion in a chose day and age, for example, birth or graduation).
Accomplice information can periodically be more beneficial to demographers than period information. Since associate information is sharpened to a particular day and age, it is typically more exact. It is more precise because of the way that it can be tuned to recover custom information for a particular report.