An empirical study of probability elicitation under noisy-OR assumption

Authors:

Adam Zagorecki and Marek J. Druzdzel
Decision Systems Laboratory
School of Information Sciences
and Intelligent Systems Program
University of Pittsburgh
135 North Bellefield Avenue
Pittsburgh, PA 15260, U.S.A.
e-mail: adamz@sis.pitt.edu, marek@sis.pitt.edu

Abstract:

Bayesian network is a popular modeling tool for uncertain domains that provides a compact representation of a joint probability distribution among a set of variables. Even though Bayesian networks significantly reduce the number of probabilities required to specify probabilistic relationships in the domain, the number of parameters required to quantify large models is still a serious bottleneck. Further reduction of parameters in a model is usually achieved by utilization of parametric probability distributions such as noisy-OR gates. In this paper report the results of an empirical study that suggests that under the assumption, that the underlying modeled distribution follows the noisy-OR assumptions, human experts provide parameters with better accuracy using elicitation of noisy-OR parameters than when eliciting conditional probability tables directly. It also seems that of the two alternative noisy-OR parameterizations due to Henrion and Diez the latter results in better elicitation accuracy.