Krause, Markus, and René Kizilcec. “To Play or Not to Play: Interactions Between Response Quality and Task Complexity in Games and Paid Crowdsourcing”. Proceedings of the AAAI Conference on Human Computation and Crowdsourcing, vol. 3, no. 1, Sept. 2015, pp. 102-9, doi:10.1609/hcomp.v3i1.13226.