Faridani, S., Buscher, G., & Xu, Y. (2013). A Ground Truth Inference Model for Ordinal Crowd-Sourced Labels Using Hard Assignment Expectation Maximization. Proceedings of the AAAI Conference on Human Computation and Crowdsourcing, 1(1), 20–21. https://doi.org/10.1609/hcomp.v1i1.13133