If the attrition rate is anything like the crypto course from coursera then around 3-4000 of those will end up finishing the course and achieving a pass.
I'm not familiar with the courses in question, but my impression is that basic statistics is much easier than basic crypto. Obviously, either one could be made arbitrarily difficult, but I've seen more people struggle with things like RSA than with T-tests and distributions.
Also, I think statistics knowledge is more relevant, especially to everyday life, than crypto. Not to say that crypto is unimportant, but statistics is applicable everywhere and changes how you view pretty much everything.
So I think there are some reasons for the stats course to have less attrition than crypto.
It would be interesting to see the attrition of other similar classes at both Udacity and Coursera.
That would be an interesting comparison, but I'm not sure what it would show. Comparative difficulty of course material? How good the platforms are? The required student time investment? Perceived rewards? All of these probably contribute in some way
It certainly is a wide new world of possibilities, especially for those of us who want to continue semi-structured learning outside of a university environment.
The success in this courses cannot be measured only by those that achieve a pass or certification. I did one of Udacity's courses, but being short on available time I didn't do all the homework or the final exam. I still learned a lot...
Which I would argue is still impressive...