I’ve read a very interesting article in one of the recents IEEE Software magazines by Darja Smite, Fabio Calefaro and Claes Wohlin:  http://www.computer.org/cms/Computer.org/ComputingNow/issues/2015/08/mso2015040026.pdf  The authors look critically at the body of knowledge in the area trying to find evidence of the cost savings. The results are that the evidence is not in the published articles. … Read more