i would like to take you through, we are going to have bob schiller on later.pretty sure he is going to prices that stock move too much to be justified by future cash flows. i think i know what you might say, but what is your responsibility? he is right. it is clear that stock prices vary more than expected cash flow. inre are two ingredients stock prices. one is expected cash flow's and the other is the discount rate, equivalent to the expected return. the fact that prices vary more justdividends cash flows, says there is variation in the discount rate that generates variation in prices. this is all well documented in the literature. something about that is irrational -- you are taking a stance on how much rational variation that can be in an expected return or discount rate. >> what does this mean to me? >> prices vary more than dividends. >> if the stock market is more volatile than it should be under one model, the model that professor shiller would have would say that future cash flows are -- back at a constant rate of return. is saying isr fama that price

20,000 students, will have taken his class, that is way over double the number of students that bob schiller has taught in his the 30 years career. >> rose: right. >> one eight week,. >> the history of the courses is they sign up for the course and drop out. >> yes, but it is free, why not? >> you have no investment. >> yes. the stuff about completion rates being low is kind of still litigate groo. >> so what we have learned of the people that complete the first assignment, 44 percent of them finish, but -- and, you know, pretty much equal number of people audit the course,. >> rose: online education will change the world? >> i think it is giving an opportunity to people, i mean it is getting people better jobs, giving them new life we have a woman in bangladesh, she was a product -- she was involved in an abusive relationship with her husband. she escaped from her situation, and a friend of hers and herself decided to start a bakery, she went online and took an accounting course, a marketing course, how to run a small business course. and this woman in bangladesh is now running a successful