We study a problem of dynamic allocation without money. Agents have
arrivals and departures and strict preferences over items. Strategyproofness
requires the
use of an arrival-priority serial-dictatorship (APSD) mechanism,
which is ex post Pareto efficient but has poor {\em ex ante} efficiency
as measured through average rank efficiency.
We introduce the
{\em scoring-rule} (SR) mechanism, which biases in favor of allocating
items that an agent values above the population consensus.
The SR mechanism is not strategyproof but has tolerable manipulability
in the sense that: (i) if every agent optimally manipulates, it reduces
to APSD, and (ii) it significantly outperforms APSD for rank efficiency
when only a fraction of agents are strategic.
The performance of SR is also robust to mistakes by agents
that manipulate on the basis of inaccurate information about
the popularity of items.
James Zou, Sujit Gujar, and David C. Parkes