SOCIALLY-OPTIMAL DESIGN OF CROWDSOURCING PLATFORMS WITH REPUTATION UPDATE ERRORS

Crowdsourcing systems (e.g. Yahoo! Answers and Amazon Mechanical Turk) provide a platform for requesters, who have tasks to solve, to ask for help from workers. Vital to the proliferation of crowdsourcing systems is incentivizing the workers to exert high effort to provide high-quality services. Reputation mechanisms have been shown to work effectively as incentive schemes in crowdsourcing systems. A reputation agency updates the reputations of the workers based on the requesters' reports on the quality of the workers' services. A low-reputation worker is less likely to get served when it requests help, which provides incentives for the workers to obtain a high reputation by exerting high effort. However, reputation update errors are inevitable, because of either system errors such as loss of reports, or inaccurate reports, resulting from the difficulty in accurately assessing the quality of a worker's service. The reputation update error prevents existing reputation mechanisms from achieving the social optimum. In this paper, we propose a simple binary reputation mechanism, which has only two reputation labels ("good" and "bad"). To the best of our knowledge, our proposed reputation mechanism is the first that is proven to be able to achieve the social optimum even in the presence of reputation update errors. We provide design guidelines for socially-optimal binary reputation mechanisms.