Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
We experimentally study contributing behavior to a threshold public good under simultaneous and sequential voluntary contribution mechanisms and investigate how refund policies interact with the mechanism. We find that, for a given refund rule, efficiency is greater under a sequential contribution mechanism than under a simultaneous contribution mechanism. Furthermore, for a given order of contributions, we find that full refund unambiguously achieves higher efficiency in the simultaneous mechanism while this is not the case in the sequential mechanism.