Advertising in the digital age bears little resemblance to the “Mad Men” depiction — the Don Drapers of advertising have been replaced by big data and the people who work with it. Harvard Business School professor John Deighton, the author of the case, “WPP: From Mad Men to Math Men (and Women),” and Sir Martin Sorrell, founder and group chief executive of WPP and the protagonist in the case, discuss how WPP has been successful in the new advertising world order where algorithms and robots rule.