Picking up a book is gratifying: look at me, not reading dumb listicles on the internet! Finishing a book, however, is a challenge. Which of this summer’s top-selling books have the highest reader attrition? Dr. Jordan Ellenberg has a semi-scientific way to find out, using buyer-generated info from Amazon to identify this year’s most unread book. It’s a charmingly simple (if not entirely rigorous) method: Dr. Ellenberg cruises the “Popular Highlights” listings for each title, which shows the five passages most frequently highlighted by Kindle readers. If most folks make it to the very last page, those passages should come from the front, the back, and everywhere in between. If everyone drops off in Chapter 3, the most popular passages will be focused in the first few pages.