I’ve always suspected that most political books go largely unread, and that people buy them either for the fad factor or to serve as reference material for later use. We finally have a measure to test that hypothesis, the Wall Street Journal reports, developed by University of Wisconsin mathematics professor Jordan Ellenberg. Ellenberg calls it the “Hawking Index” in honor of physicist Stephen Hawking, whose book A Brief History of Time is reportedly “the most unread book of all time.” Ellenberg lays out his method:

How can we find today’s greatest non-reads? Amazon’s “Popular Highlights” feature provides one quick and dirty measure. Every book’s Kindle page lists the five passages most highlighted by readers. If every reader is getting to the end, those highlights could be scattered throughout the length of the book. If nobody has made it past the introduction, the popular highlights will be clustered at the beginning.

Thus, the Hawking Index (HI): Take the page numbers of a book’s five top highlights, average them, and divide by the number of pages in the whole book. The higher the number, the more of the book we’re guessing most people are likely to have read. (Disclaimer: This is not remotely scientific and is for entertainment purposes only!)

Be sure to bear that disclaimer in mind. For instance, I make frequent use of highlights in books for study, but less so with books I read for entertainment — which are few and far between these days, alas. The Kindle system also provides rough measures of farthest spot read, but that’s (a) not readily available to outsiders and is used more for synchronizing between devices, and (b) is also deceptive, because it will mark a “farthest read” point when just looking up a passage. Ellenberg’s Hawking Index is probably the best we’ll get as a metric for actual reads, at least in the near future.

Hawking’s book does indeed come in near the bottom of Ellenberg’s list, but not dead last. That honor belongs to this year’s fad read, Capital in the Twenty-First Century by Thomas Piketty, with a Hawking Index of 2.4%. The deepest penetration of the top five most popular highlights comes on page 26 … out of almost 700. The issue with Capital might be that the discovery of serious flaws in Piketty’s data discouraged people from bothering to read the book even after they spent money on it.

What happens when applying the Hawking Index to books written by political figures? The Washington Post’s Philip Bump takes a look, and the results aren’t exactly flattering to Hillary Clinton:

So, naturally, we decided to apply this methodology to “Hard Choices” and other recent or comparable political books. And we have our own ranking, which we now present in order from estimated-least- to estimated-most-read.

1. “Hard Choices,” by Hillary Clinton. Hawking Index: 2.04 percent.
Well, there you have it. The deepest into Hard Choices the popular highlights get is page 33, a quote about smart power. Three of the five most-popular highlights occur within the first 10 pages. We will note the same caveat that Ellenberg applies to Piketty. “Hard Choices” is fairly new, and fairly long. Still, though, one would think more people had made it past page 33.

The most popular quote? “Do all the good you can, at all the times you can, to all the people you can, as long as ever you can.” Which, like several of the top quotes from the authors listed below, isn’t actually a quote from Hillary Clinton. Instead, it’s a mantra from her family’s Methodist faith.

That’s actually a worse score than Piketty’s book gets, although the penetration is a bit deeper. George W. Bush’s Decision Points gets a 19.1%, if I’ve done the Hawking Index math correctly, which outdoes everyone on this list except Robert Gates. Two of the five most popular highlights land on pages 190 and 195 of the 512-page book, with the latter being the most popular — and a quote from Abraham Lincoln. Interestingly, it outperforms both of the original Clinton memoirs, too.

All that said, don’t read too much into this. It’s likely that some of the book sales (especially Kindle) have been for the purpose of reference material for the upcoming presidential election, and reviews have already noted that there isn’t much worth highlighting in this latest memoir from the former Secretary of State. The bigger problem for the Clintons is the book sales themselves, which have plummeted in week 2 and again in week 3:

Do you own a hard copy of Hillary Clinton’s book Hard Choices? If so, you’re in exclusive company. According to data provided to the Post by Nielsen BookScan, a little over 26,000 more copies of the book were sold in its third week — down almost 46 percent from the week prior, which was down 44 percent from the week before that.

It has sold about 160,000 copies in hard cover, total — just a little less than the population of Salem, Oregon. It’s sold one book for every 411 Obama voters in the 2012 general election, fewer copies than there were Obama voters in every state besides the Dakotas, Alaska and Wyoming. If every Obama voter in Idaho had bought the book, it would have done 32.5 percent better. Enough people bought Hard Choices that they couldn’t all fit into Michigan Stadium in Ann Arbor, but only 50,000 people would have to have someone sit on their laps. …

Other things that went down 46 percent: Target’s stock price, after a massive security breach was discovered. Viewership of golf’s U.S. Open in 2014, without Tiger Woods. Nielsen ratings between Obama’s first and second inaugural addresses.

Even Howard Fineman noted that the book sales are eating into the “Inevitability v2.0” argument for Hillary Clinton.

Addendum: On the other hand, if you want a real page turner, there’s always …

Regnery has a new paperback edition release out today, with a new foreword written by me (and with a nice cover credit, too). If you read this back when it was first released 13 years ago, pick up a fresh copy — and if you’ve never read it, you owe it to yourself to do so now. (Note: My foreword does not appear in the Kindle version.)