[the_watcher]

I've worked in this industry a bit, and MOOCs rarely use "course completion" as their primary success metric. One reason is precisely what you mentioned - that many people simply take the course for as long as they need to get their desired value out of it, then leave. Another was that the team I worked with found that, by far, the single biggest factor in terms of course completion was that a third party (usually their boss) incentivized them to complete it, and of those people, they were more likely to find ways to skip sections, get the minimum scores required to pass, etc.

[gmiller123456]

So what ways do they measure success? I can attest that I have never started a course just for a few lectures, and I've always planned on taking the whole course. I've quit the majority of courses just because they weren't any good (usually poorly designed homework). I have quite some because they moved on to topics that I didn't find interesting, but I never looked at them from the beginning and said "That's where I'm going to stop". The ones I have completed were ones I thoroughly enjoyed, and felt like I learned a lot.

So just from a "course completion" point of view, I'd think it'd be hard to tell the difference between courses I liked, but moved on to topics I didn't like, vs. the ones I just thought weren't any good. But the fact that I stuck with some courses all the way through should at least be good for something.

[the_watcher]

They'll usually _track_ course completion, but it's not necessary for a course to have a high, or even an average completion rate to be a successful course. From what I've seen, they'll track active time spent in course, how much of the course is completed, use quizzes to reinforce learnings while also getting a check in on how actively the student has been taking the course, etc. They also rely on ratings and qualitative feedback. It's not as precise as something like "completions", but from what I've seen it's reasonably effective at assessing course value.