Bayes-Optimal Effort Allocation in Crowdsourcing: Bounds and Index Policies
Abstract
We consider effort allocation in crowdsourcing, where we wish to assign labeling tasks to imperfect homogeneous crowd workers to maximize overall accuracy in a continuous-time Bayesian setting, subject to budget and time constraints. The Bayes-optimal policy for this problem is the solution to a partially observable Markov decision process, but the curse of dimensionality renders the computation infeasible. Following a similar approach to the Lagrangian Relaxation technique in Adelman and Mersereau (2008), we provide a computationally tractable instance-specific upper bound on the value of this Bayes-optimal policy, which can in turn be used to bound the optimality gap of any other sub-optimal policy. In an approach similar in spirit to the Whittle index for restless multi-armed bandits, we provide an index policy for effort allocation in crowdsourcing and demonstrate numerically that it outperforms other state-of-the-art policies and performs close to optimal.
BibTeX
@InProceedings{pmlr-v51-hu16a,
title = {Bayes-Optimal Effort Allocation in Crowdsourcing: Bounds and Index Policies},
author = {Hu, Weici and Frazier, Peter},
booktitle = {Proceedings of the 19th International Conference on Artificial Intelligence and Statistics},
pages = {324--332},
year = {2016},
editor = {Gretton, Arthur and Robert, Christian C.},
volume = {51},
series = {Proceedings of Machine Learning Research},
address = {Cadiz, Spain},
month = {09--11 May},
publisher = {PMLR},
pdf = {http://proceedings.mlr.press/v51/hu16a.pdf},
url = {https://proceedings.mlr.press/v51/hu16a.html},
abstract = {We consider effort allocation in crowdsourcing, where we wish to assign labeling tasks to imperfect homogeneous crowd workers to maximize overall accuracy in a continuous-time Bayesian setting, subject to budget and time constraints. The Bayes-optimal policy for this problem is the solution to a partially observable Markov decision process, but the curse of dimensionality renders the computation infeasible. Following a similar approach to the Lagrangian Relaxation technique in Adelman and Mersereau (2008), we provide a computationally tractable instance-specific upper bound on the value of this Bayes-optimal policy, which can in turn be used to bound the optimality gap of any other sub-optimal policy. In an approach similar in spirit to the Whittle index for restless multi-armed bandits, we provide an index policy for effort allocation in crowdsourcing and demonstrate numerically that it outperforms other state-of-the-art policies and performs close to optimal.}
}