Personalized Thread Recommendations for MOOC Forums

Social learning, i.e., students learning from each other through social interactions, has the potential to significantly scale up instruction in online education. In many cases, such as in massive open online courses (MOOCs), social learning is facilitated through discussion forums hosted by course providers. We propose a probabilistic model for the process of learners posting on such forums, using point processes. Different from existing works, our method integrates topic modeling of the post text, timescale modeling of the decay in post activity over time, and learner topic interest modeling into a single model, and infers this information from user data. Our method also varies the excitation levels induced by posts according to the thread structure, to reflect typical notification settings in discussion forums

Two mathematical tools useful in recommender systems are the linearized binary regression and the Rasch model.

The Rasch model is widely used for item response analysis in applications ranging from recommender systems to psychology, education, and finance. While a number of estimators have been proposed for the Rasch model over the last decades, the available analytical performance guarantees are mostly asymptotic. We develop a framework that relies on a novel linear estimator to provide guidelines on the number of items and responses required to attain low estimation errors in tests or surveys.

Probit regression was first proposed by Bliss in 1934 to study mortality rates of insects. Since then, an extensive body of work has analyzed and used probit or related binary regression methods (such as logistic regression) in numerous applications and fields. We provide a fresh angle to such well-established binary regression methods; we demonstrate that linearizing the probit model in combination with linear estimators performs on par with state-of-the-art nonlinear regression methods, such as posterior mean or maximum aposteriori estimation, for a broad range of real-world regression problems. We derive exact, closed-form, and nonasymptotic expressions for the mean-squared error of our linearized estimators, which clearly separates them from nonlinear regression methods that are typically difficult to analyze.


Lan, A. S., Spencer, J. C., Chen, Z., Brinton, C. G., & Chiang, M. Personalized thread recommendation for MOOC discussion forums. In Joint European Conference on Machine Learning and Knowledge Discovery in Databases. September 2018

Lan, Andrew S., Mung Chiang, and Christoph Studer. "An estimation and analysis framework for the Rasch model." International Conference of Machine Learning (2018).

Lan, Andrew S., Mung Chiang, and Christoph Studer. "Linearized binary regression." 2018 52nd Annual Conference on Information Sciences and Systems (CISS). IEEE, 2018.