Subgroup Discovery in MOOCs: A Big Data Application for Describing Different Types of Learners

Abstract

The aim of this paper is to categorize and describe di erent types of learners in mas- sive open online courses (MOOCs) by means of a subgroup discovery approach based on MapReduce. The nal objective is to discover IF-THEN rules that appear in dif- ferent MOOCs. The proposed subgroup discovery approach, which is an extension of the well-known FP-Growth algorithm, considers emerging parallel methodologies like MapReduce to be able to cope with extremely large datasets. As an additional feature, the proposal includes a threshold value to denote the number of courses that each discovered rule should satisfy. A post-processing step is also included so redundant subgroups can be removed. The experimental stage is carried out by con- sidering de-identi ed data from the rst year of 16 MITx and HarvardX courses on the edX platform. Experimental results demonstrate that the proposed MapReduce approach outperforms traditional sequential subgroup discovery approaches, achiev- ing a runtime that is almost constant for di erent courses. Additionally, thanks to the nal post-processing step, only interesting and not-redundant rules are discov- ered, hence reducing the number of subgroups in one or two orders of magnitude. Finally, the discovered subgroups are easily used by courses' instructors not only for descriptive purposes but also for additional tasks such as recommendation or personalization.