<title>Abstract</title> <italic>Fair employment policies constrain employee selection: specifically, applicants’ professional experience can be a substitute for formal education. However, reflecting firm-specific job requirements, this substitution rule applies less strictly to applicants from outside the firm....</italic>

Adverse selection induces economic limits to market substitution. If quality uncertainty persists in both Internet and traditional marketplaces, a second-best equilibrium with parallel market segments may arise. The information cost advantage of one marketplace is exactly offset by a more severe...