"Two-hit wonders" quantified

An author is a "two-hit wonder" to the extent that there is a small difference in popularity between the most and second-most popular of his works, and a large difference between the second and the third. Thus, if a, b, and c are numbers representing the popularity of an author's three most popular works, then the greater the value of b²/ac, the more of a "two-hit wonder" that author is.

The values for a, b, and c can be acquired by checking the author page on LibraryThing, which lists how many copies of each book are owned by members of that site. (This is easier than checking Amazon, because LT combines the various editions of each book.)

Take George Orwell, for instance, as a pretty clear example of a two-hit wonder. His top three works on LT are 1984 (64,964), Animal Farm (46,341 copies), and Down and Out in Paris and London (6,378). There are also 2,625 copies of books that combine Animal Farm and 1984 in a single volume, so:

• a (1984) = 64,964 + 2,625 = 67,589
• b (Animal Farm) = 46,341 + 2,625 = 48,966
• c (Down and Out) = 6,378
• b²/ac = 5.56

For comparison, Herman Melville is an obvious example of a one-hit wonder.

• a (Moby-Dick) = 27,517
• b (Bartelby) = 2,121
• c (Billy Budd) = 2,094
• b²/ac = 0.08

Charles Dickens wrote a large number of popular books.

• a (Great Expectations) = 30,222
• b (A Tale of Two Cities) = 28,643
• c (Oliver Twist) = 18,408
• b²/ac = 1.47

Now that the metric is established, and has been shown by a few examples to give reasonable results, we can try to determine which English-language authors are the greatest two-hit wonders. This post was inspired by a post by Bruce Charlton called "Tolkien - the only 'Two Hit Wonder'?" -- so let's look at Tolkien first. Tolkien's case is complicated somewhat by the fact that The Lord of the Rings, a single novel, is very often sold in three volumes, so to get the number I took the total number of one-volume copies, divided the numbers for Fellowship, Towers, and Return by three, and added them all together. The result is:

• The Lord of the Rings = 87,087
• The Hobbit = 80,389
• The Silmarillion = 26,894
• b²/ac = 2.76

So Tolkien is indeed a two-hit wonder to some extent, but to nowhere near the same degree as Orwell. (This result surprised me a bit. I had underestimated the popularity of The Silmarillion.)

Here, then, is a ranked list of some two-hit wonders (score at least 2).

• Anne Brontë = 22.73 (The Tenant of Wildfell Hall, Agnes Grey)
• Samuel Butler = 14.93 (The Way of All Flesh, Erewhon)
• Lewis Carroll = 11.39 (Alice's Adventures in Wonderland, Through the Looking-Glass)
• Barack Obama = 10.58 (The Audacity of Hope, Dreams from My Father)*
• Samuel Richardson = 9.38 (Pamela, Clarissa)
• Wilkie Collins = 6.26 (The Woman in White, The Moonstone)
• George Orwell = 5.56 (1984, Animal Farm)
• Richard Wright = 4.74 (Native Son, Black Boy)
• Thornton Wilder = 4.48 (Our Town, The Bridge of San Luis Rey)
• Jack London = 2.88 (The Call of the Wild, White Fang)
• J. R. R. Tolkien = 2.76 (The Lord of the Rings, The Hobbit)
• Henry Fielding = 2.60 (Tom Jones, Joseph Andrews)
• Mark Twain = 2.08 (Huckleberry Finn, Tom Sawyer)
• Rider Haggard = 2.01 (King Solomon's Mines, She)

So far these are the only ones we (I and various commenters here and on Bruce's original post) have found. (Poets and playwrights have proved hard to analyze, as it is so common for several different works to be sold together in one volume, so I have mostly limited this to novels.)  Feel free to add more in the comments.

* Apparently Bill Ayers has repeatedly claimed to be the real author of Dreams of My Father but not of The Audacity of Hope. If that's true (goodthinkers say he's just joking), then of course Obama doesn't count as a two-hit wonder.