  The matching literature often recommends market centralization under the
assumption that agents know their own preferences and that their preferences
are fixed. We find counterevidence to this assumption in a quasi-experiment. In
Germany's university admissions, a clearinghouse implements the early stages of
the Gale-Shapley algorithm in real time. We show that early offers made in this
decentralized phase, although not more desirable, are accepted more often than
later ones. These results, together with survey evidence and a theoretical
model, are consistent with students' costly learning about universities. We
propose a hybrid mechanism to combine the advantages of decentralization and
centralization.
  Published at The Journal of Political Economy under a new title, ``Preference
Discovery in University Admissions: The Case for Dynamic Multioffer
Mechanisms,'' available at https://doi.org/10.1086/718983 (Open Access).
