Before revision:  For an empirical study of matching markets, the main statistics of interest are  the matching frequencies, which show the fraction of students of a given type who match with colleges of a given type.
After revision:  For an empirical study of a two-sided large matching market (such as a college admissions problem), the primary statistics of interest are the matching frequencies, which show the fraction of students of a given type who match with colleges of a given type.