http://blogs.technet.com/b/machinelearning/archive/2015/01/14/new-research-brings-precision-to-sampling-methods-used-in-statistics-and-machine-learning.aspx
http://blogs.technet.com/b/machinelearning/archive/2015/01/14/new-research-brings-precision-to-sampling-methods-used-in-statistics-and-machine-learning.aspx