We identify four subpopulations of interest within each course, to illustrate the considerable variability in registrants by their actions. Figure 2 provides a screenshot of the edX interface to illustrate these distinctions. Among registrants, we define those who “viewed” the course as those who accessed the “courseware” tab on edX, the leftmost tab in Figure 2, where the core content of the course, including video and assessments, generally reside. Note that it is possible to view course information, the syllabus, and discussion forums, and still not “view” the course, by this definition. Among those who “viewed” the courseware, we define those who “explored” as those who accessed half or more of the “chapters” in the courseware. Figure 2 also illustrates chapters, which are the highest organizational units in the courseware. To become a “viewer,” a registrant must merely “click” on the courseware. To become an “explorer,” the viewer must click on content within half or more of the chapters.
Figure 2. Screenshot of the edX interface from HeroesX, with the “courseware” shown on the left. Registrants must click on the “courseware” to meet the definition of “viewed,” and they must click on half or more of the “chapters” (the primary tabs on the left, in this case, CB22X: Coming Soon, Hour 0, Hour 1…) to meet the definition of “explored.”
The cutoff that distinguishes viewers from explorers is arbitrary, but it is one way to identify registrants who appear to access substantial amounts of the courseware. The sidebar to the right further identifies mutually exclusive and exhaustive categories of course registrants. Of particular interest may be those who “only explore,” that is, those who access substantial amounts of the courseware but appear to be uninterested or unsuccessful when it comes to certification. Note the difference between “explored” and “only explored,” where the former overlaps with certified registrants and the latter explicitly excludes them. The last category describes certified registrants, those whose weighted average score, expressed as a percentage, is above the instructor-selected minimum cutoff percentage. This cutoff ranges from 50% to 60% across MITx courses and from 50% to 80% across HarvardX courses.