Modeling manpower systems in two-grade organizations

Organizations whose work force consists of `trainees´ on the one hand and `regular employees´ on the other (e.g. nontenured versus tenured faculty) are considered. A model which allows direct recruitment into both grades and assumes seniority dependent promotion policy and resignation patterns is formulated. Formulas for actual promotion and resignation densities are then derived. The model is used to predict time-dependent expected grad size trajectories as a function of recruitment patterns. Specifying promotion and resignation densities, we derive quantities of interest for two different types of organizations, one in continuous and the other in discrete time. Illustrative numerical examples are provided for these special cases.