Sunday, November 12th, 2006

BookSuggester and UnSuggester

People do not generally like BOTH Shopaholic and Critique of Pure Reason.

The “real” news today is the debut of BookSuggester, a new feature designed to expose LibraryThing’s excellent and varied recommendations to members and non-members alike. We put them alongside Amazon’s, which are also quite good. We are proud of our recommendations, but haven’t perfected the perfect algorithm yet. When we’ve made things as good as we can, we’re going to start offering recommended book data to libraries.**

But to heck with that! Let’s talk about bad recommendations. Today we introduce UnSuggester, “the worst recommendation system ever devised™.”

UnSuggester is a brand new idea in recommender technology. Recommender systems usually work by similarities. Amazon’s “Customers who bought this item also bought” and LibraryThing’s “People with this book also have” are typical of the type—What books do people buy together? What books occur often in the same member libraries?

UnSuggester flips this logic: What books DON’T occur in the same libraries? We took our “similars” algorithm and changed “sort ascending” to “sort descending” and—hey presto!—instead of similar books, we get opposite ones. You bet we’re going to patent it!

How does it work?

UnSuggester starts by finding every copy of the book in question and all of its owners. So, taking Thucydides’ History of the Peloponnesian War as an example, LibraryThing finds the 600-odd people who have entered this ancient classic in their account. Then it makes a big pile of all their other books, a pile of some 623,000 books in all. Then it does a little math. If LibraryThing has seven million books, then a pool of 623,000 book is about 8% of the total. If this pool were average, it would also contain 8% of the Harry Potters, 8% of the Derridas and 8% of the Danielle Steels. But this isn’t so. People who own Thucydides aren’t a random cross-section of the book-loving public. For example that 8% also contains almost half the Caesar and Plutarch in LibraryThing. At the other end of the scale, Thucydides-fanciers are particularly immune to the novels of Marian Keyes and Dean Koontz. The greatest disconnect occurs with Louise Rennison’s popular, teeny-bopper chick-lit novel Angus, thongs and full-frontal snogging : confessions of Georgia Nicolson—the top UnSuggestion.

What patterns emerge?

The Mists of Avalon and Desiring God are very uncommon shelf-mates.

Play with it a few minutes, and patterns emerge. Philosophy and postmodern literary criticism oppose chick lit, popular thrillers and the young adult section. Programming does not truck with classic literature. Memoirs of depression, like Prozac Nation, meet their match in the cheery The Night Before Christmas. Ann Coulter and David Sedaris do not see eye-to-eye. There is a strong disconnect between readers of much recent Protestant, mostly evangelical, non-fiction, and large swaths of contemporary literary fiction. For example, LibraryThing includes 2,300 readers who’ve logged Jeffrey Eugenides’ epic gender-bender novel Middlesex, and 222 readers of John Piper’s The Passion of the Christ: 50 Reasons He Came to Die. But the groups don’t overlap. No reader has both. Similar instances occur again and again.

These disconnects sadden me. Of course readers have tastes, and nearly everyone has books they’d never read. But, as serious readers, books make our world. A shared book is a sort of shared space between two people. As far as I’m concerned, the more of these the better.

So, in the spirit of unity and understanding, why not enter your favorite book, then read its opposite?

By the way, how about putting this up on or Digg? Wait, we have a Digg now.*

*LibraryThing never been Dugg. But recently a pale immitation of LibraryThing was lofted to the heavens as the first social network for books. For one day Digg gave them twice our traffic. Fortunately, they fell like a stone after that and, this morning, Alexa has them at “too low to measure.”
**My friend Ben correctly points out to me that he suggested “find your book nemesis” almost a year ago.

Labels: 1


Leave a Reply