Is this really the 80-20 rule? As I understood it, the 80-20 rule is that 80% of the effects come from 20% of the causes. E.g. 80% of profits come from 20% of y

Is this really the 80-20 rule? As I understood it, the 80-20 rule is that 80% of the effects come from 20% of the causes. E.g. 80% of profits come from 20% of your clients. Here he's saying that 20% of developers want to launch a startup, and that you can further subdivide each group into another group that is 20% of the size of the previous group. That doesn't make sense to me as an application of the 80-20 rule other than that there's a 20% in there. Edit: here's an explanation. http://en.wikipedia.org/wiki/Pareto_principle http://en.wikipedia.org/wiki/Pareto_principle