Incentivizing participation in online forums for education

Abstract

We present game-theoretic model for online forums for education, where students in class can post questions to the forum and seek responses from the instructor or other students in the class. We first show that our model predicts the anecdotally observed phenomenon that students' participation in forum is non-monotone in the instructor's response rate to questions: if the instructor responds at too high rate students do not respond to their peers' questions, whereas an almost-absent instructor induces very little participation from the students as well. We then investigate the optimal use of forum for two kinds of questions--- single-answer questions and discussion-style questions--- which lead to different levels of rewards that can be meaningfully offered. We show that for discussion-style questions, the instructor can choose response rate so that the expected rate at which the first student response is received increases linearly with the size of the class; for single-answer questions, however, the optimal expected rate of arrival of the first student response remains constant even as class size diverges. However, this slow response rate can be remedied by mixing types--- as long as there is any positive probability of a discussion-type question in forum, the instructor can choose her response rate so that the equilibrium rate of the first response from the class diverges with the number of students in the class.