Here’s something interesting for publishers: a US physics professor called Didier Sornette (pictured) has figured out how to analyse and predict book sales by adapting methods used to study earthquakes and financial markets.

According to the Technology Review website,

Book publishing houses and marketing firms could use the method to quantify how books will sell post-peak, and to time the market, according to the researchers.

Sornette’s model is apparently 84 percent accurate, and could be put to practical use within six months to a year. The UCLA physicist and complex systems theorist used statistical physics and mathematics to analyze 138 books that made Amazon.com's best-seller list between 1997 and April 2004, and published the results in the journal Physical Review Letters.

A press release explains Sornette’s findings in more detail:

Best-selling books typically reach their sales peaks in one of two ways. The less potent way is by what Sornette calls an "exogenous shock," which is brief and abrupt. An example is Strong Women Stay Young by Dr. Miriam Nelson, which peaked on the list the day after a favorable review in the Sunday New York Times. A second example is Sornette's own 2002 book, Why Stock Markets Crash: Critical Events in Complex Financial Systems, which spiked following a favorable review by Jon Markman on CNBC and TheStreet.com. "On Jan. 17, 2003, my book was ranked 2,000-something and then suddenly it was No. 17," Sornette recalled. "A few hours later, it was in the top 10. As a physicist, it looked to me like an exogenous shock to the system."

Sales are typically greater, however, when a book benefits from what Sornette calls an "endogenous shock," which progressively accelerates over time, and is illustrated in the book business by favorable word-of-mouth. Such books rise slowly, but the sales results are more enduring, and the decline in sales is slower and more much gradual, he found.

An example includes The Divine Secrets of the Ya-Ya Sisterhood, which reached the best-seller list two years after it was published, without the benefit of a major marketing campaign. The book was popular with book clubs and inspired women to form "Ya-Ya Sisterhood" groups of their own. A second example is Nora Roberts' novel, Heaven and Earth (Three Sisters Island Trilogy), which peaked only after a slow rise and also fell slowly, which Sornette attributes to word of the book spreading among friends and family.

The slower peaks tend to generate more sales over time, Sornette said.

"Word-of-mouth can spread like an epidemic," he said.

The trajectories of many books' rankings are combinations of both kinds of peaks, Sornette says, which suggests that an effective, well-timed marketing campaign could combine with a strong network to enhance sales.

That’s food for thought: the small size of most New Zealand book sales means that publishers need to use every trick in the book to sell their books.