Have you started a highly acclaimed book only to find it so tedious that you couldn't finish it? Jordan Ellenberg, a University of Wisconsin mathematics professor, has figured out how to tell which best-sellers are the most boring. In the Kindle version of each book, Ellenberg pointed out in The Wall Street Journal last week, there is a list of the five passages most highlighted by readers. When most of the highlights occur in the first half of a book, it would suggest that many readers gave up before reaching the second. By that measure, the year's most unread best-seller is Capital in the Twenty-First Century by Thomas Piketty, a 700-page polemical treatise on economic inequality. All five of the popular highlights occur before page 27 — less than 4 percent of the way through. Conclusion: Lots of people feel cooler and smarter for having bought Piketty's weighty tome, though it gathers dust on their night tables.

The Kindle formula also works with fiction. Ellenberg's dullness detector uncovered a curious phenomenon among readers of The Goldfinch by Donna Tartt, which won the Pulitzer Prize this year. The five most popular highlights all occur in the last 20 pages of the 771-page novel. Is that a compliment? I suspect not. The Goldfinch is one of those self-conscious "masterpieces'' that some readers and critics adore — and some, like me, find bloated and self-indulgent. To get to the end, I found myself skimming over dense chunks of pointless description and meandering subplots. Perhaps The Week has heightened my appreciation for brevity, but I think Tartt's novel would benefit if it were cut by, say, 250 pages. Kindle doesn't lie: To be read more, write less.