On The Gist, how much sanity does it cost to change a lightbulb?   In the interview, babies don’t come with instructional manuals, but the publishing industry is more than ready to bombard new parents with the latest, always evolving wisdom on how to raise a human right. But Emily Oster’s new book is a rare scientific look at child-rearing, grounded in her expertise as a rational economist and her experience as an anxious mother. Oster is the author of Cribsheet: A Data-Driven Guide to Better, More Relaxed Parenting, from Birth to Preschool.    In the Spiel, president Trump’s directionless foreign policy is on full display against Iran.Learn more about your ad choices. Visit megaphone.fm/adchoices