  Quality control plays a critical role in crowdsourcing. The state-of-the-art
work is not suitable for large-scale crowdsourcing applications, since it is a
long haul for the requestor to verify task quality or select professional
workers in a one-by-one mode. In this paper, we propose a misreport- and
collusion-proof crowdsourcing mechanism, guiding workers to truthfully report
the quality of submitted tasks without collusion by designing a mechanism, so
that workers have to act the way the requestor would like. In detail, the
mechanism proposed by the requester makes no room for the workers to obtain
profit through quality misreport and collusion, and thus, the quality can be
controlled without any verification. Extensive simulation results verify the
effectiveness of the proposed mechanism. Finally, the importance and
originality of our work lie in that it reveals some interesting and even
counterintuitive findings: 1) a high-quality worker may pretend to be a
low-quality one; 2) the rise of task quality from high-quality workers may not
result in the increased utility of the requestor; 3) the utility of the
requestor may not get improved with the increasing number of workers. These
findings can boost forward looking and strategic planning solutions for
crowdsourcing.
