a system for yield management comprising an application server that provides a web application where e - commerce managers may define cohorts and pricing policies , a web server that provides a web - based interface for interacting with the application server as well as a web - based interface where clients may query for pricing policies , a reporting server that computes aggregate statistics on cohorts , a cohorting server that computes cohort definitions , and an administration server that contextualizes cohort metrics for use in reporting operations .