Tim Harford investigates one of the most popular questions from More or Less listeners: “Are there more people alive today than have ever lived?” It is a zombie statistic that every time it is laid to rest it rises again. He also looks at whether science fiction writer Arthur C Clarke was right when he suggested that behind every living person are 30 ghosts. He also investigates the strange story of Michelle Obama’s shopping trip to a lingerie store in New York. Can she really have spent $50,000 on underwear? This programme was originally broadcast on the BBC World Service.