I've written several times about why completion rates are not particularly relevant when it comes to MOOCs. Most of the students are studying out of pure interest in their limited spare time and if more important things happen in their lives they will naturally drop the course. However if you really want to keep most students' attention for the full duration of your course the answer is to make the course as short as possible. Given people's busy schedules it's best to break learning into bite-sized modules where you can "complete" a course after say 2-3 weeks while your enthusiasm lasts and momentum is up. Instead of offering a 12 week course, divide it into say 4 x 3 week modules. Short term targets feel more achievable. My MOOC efforts haven't lasted past the week 3 mark yet so I can identify with this model. I simply can't commit my evenings to a MOOC for many weeks in advance but 2-3 weeks would probably work.
This is the subject of an article by George Anders in LinkedIn, Education Pioneer's Advice: Beat the Clock. It seems Andrew Ng, co-founder of MOOC provider Coursera, has drawn the conclusion that Coursera's courses should be short and sweet instead of simply following academic tradition with twelve week courses that inevitably suffer from very low completion rates, no matter how good the course material and pedagogical approach.
"Why not take a fresh look? Internal Coursera data shows that drawn-out classes consistently suffer from higher dropout rates. The actual teaching may be impeccable. But as Ng puts it, "life gets in the way" for many of Coursera's students. The site attracts learners in all walks of life, from cab drivers to corporate vice presidents. Full-time students represent only a minority of the overall enrollee population. So class-takers typically struggle to clear out time in the midst of on-the-job demands, business travel, family illnesses and car repairs."
The global success of TED talks is further proof of our preference for shorter chunks of input. The 10-15 minute lecture can captivate and inspire in a way that the traditional academic 45-60 minute version patently fails to do. Shorter courses or modularisation of longer courses provide clear short-term goals for even the busiest learners. Many campus courses are also being divided into bite-sized chunks by awarding badges for successful completion thereby encouraging students to focus on one step at a time. Learning - one bite at a time.
See also George Anders' article in Forbes, Coursera's Online Insight: Short Classes Are Education's Future.