Ghazarian, S., R. Weischedel, A. Galstyan, and N. Peng. “Predictive Engagement: An Efficient Metric for Automatic Evaluation of Open-Domain Dialogue Systems”. Proceedings of the AAAI Conference on Artificial Intelligence, vol. 34, no. 05, Apr. 2020, pp. 7789-96, doi:10.1609/aaai.v34i05.6283.