Before revision:  In my model, the observed matching of workers to firms is the outcome of a discrete, two-sided matching process where firms with heterogeneous preference rankings over education sequentially choose workers according to an index correlated with worker preference rankings over firms- the index being a simple and flexible way to model frictions .
After revision:  In my model, the observed matching of workers to firms is the outcome of a discrete, two-sided matching process where firms with heterogeneous preference rankings over education sequentially choose workers according to an index correlated with worker preferences over firms .