This paper describes, compares, and contrasts two mathematical models of personnel movement through a hierarchical organization. The first model is a Markov chain, which is described in detail in other literature. The emphasis in this paper is on a cohort model based on people's lifetime behavior in the system. Data from student enrollments is used in comparing the models, and predictions are made and compared with numbers from real situations.Office of Naval ResearchOffice of Institutional Research at the University of California at BerkeleyFord FoundationNR047-096Approved for public release; distribution is unlimited.