TAMARA KEITH, HOST:
We've all done it - bought an important timely book with great intentions of tearing through it. But then reality sets in. We find ourselves less and less motivated to make it to the end. Author and mathematician Jordan Ellenberg wanted to quantify this phenomenon and has come up with a way to measure when exactly a reader gives up. He's with us from his office at the University of Wisconsin at Madison. Welcome.
JORDAN ELLENBERG: Hi. Thanks for having me.
KEITH: So you call your index the Hawking Index. Why is that?
ELLENBERG: Well, that's after Stephen Hawking's book "A Brief History Of Time" which is a huge bestseller and many people read it, of course, but probably many more people didn't read it. It's sort of famous as a book that many, many people bought and didn't make it all the way through.
KEITH: How does the index work? And we should also be very clear that this is completely unscientific and totally for fun.
ELLENBERG: Absolutely, yeah. So what I did was when you highlight books on your Kindle, when you highlight a sentence that you particularly like, Amazon is keeping track of that - I'm not sure everyone knows that - and Amazon records what five sentences in a book are the most commonly highlighted. So in a book that people are reading all the way through, it might be the case, that those highlights are scattered all the way through the length of the book. But if, on the other hand, there was a book that almost everyone was starting and reading a few pages and then putting down, then all of those highlights would have to be clustered in the first part. So what I did was just average the location of the top five highlights in the book - a very simple measure.
KEITH: And that's publicly available data?
ELLENBERG: Yeah. On the Kindle page for the book it'll show you the top five highlights.
KEITH: And one of the worst ranked books, according to this metric, is Hillary Clinton's "Hard Choices." We were fascinated to see that the deepest into the book that the popular highlights go is page 33.
ELLENBERG: Yeah. And it's not a short book. And it's a bit unfair to Hillary because of course the book just came out and it's up against books that have been out quite a bit longer, so people may still be on route. Nonfiction books in general score badly - although admittedly, not as badly as "Hard Choices." And I think the reason for that is because of introductions. People like to highlight direct statements - thesis statements, so to speak. And those are often found in the introductions, so that's a popular source of highlights.
KEITH: What are the books that people actually do finish? Donna Tartt's "Goldfinch" was up there on the list.
ELLENBERG: You know, a 700-page, literarily acclaimed novel seems like exactly the kind of thing you would think people would buy aspirationally and not finish. But apparently, lots of people really are getting to the end and they like what they're finding at the end.
KEITH: What made you want to develop this index?
ELLENBERG: The reason I was doing this, you know, I have my own book out. Of course, like any author, I was looking at my own metrics and I looked at the highlights and found that they were all from the first 3 chapters and I was kind of upset. But being a mathematician I started to look at other books too and then I saw that I was actually sort of ahead of the pack.
KEITH: Jordan Ellenberg is the author of the book "How Not To Be Wrong: The Power Of Mathematical Thinking." This is NPR News.
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