Facebook. Twitter. Amazon. Frequent-flyer numbers. Loyalty cards. Every day, we share personal information while buying something, trying to gain access or perks, or engaging in some other ordinary activity. In a discussion of his revealing new book, Adam Tanner illustrates how each bit of personal data we surrender can be combined with alarming speed into a personal profile that corporations, marketing services, and more nefarious entities use to their own advantage. Nobody does it better, he says, than Caesars Entertainment Corporation, whose Harrah’s North Kansas City casino — and its savvy senior vice president and general manager, Tom Cook — figure prominently in What Stays in Vegas. Tanner is a fellow at Harvard University’s Institute for Quantitative Social Science.