12/13/2004 05:50:00 AM 
sornette's home page
Soernette used statistical physics and advanced mathematics to explore 138 books that were Amazon best sellers between the periods 1997 to April 2004.
He found two ways that books can succeed.
One he calls "the exogenous shock", this is when the book receives a favorable review from a respected source or a couple of news sources.
The other is an "endogenous shock," this is when a book's sales accelerate over time. One example is the Divine Secrets of the Ya Ya Sisterhood, that took two years to reach the best-seller list. Word-of-mouth accelerated over time and allowed the book to bubble-up to bestseller status. Books that experience "endogenous shock" are usually more successful, because their sales curve is sustained for longer.
sornette's amazon analysis
There are clearly some parallels here with marketing and advertising, suggesting brand success requires both "endo" and "exogenous shocks". To succeed we need both- "exo"-in the form of a marketing campaign to get the idea out and then a series of "endo" efforts to accelerate grassroots word of mouth.
Obviously, brands can't afford to wait for sales effects, so "exo" efforts matter, but the secret is sustaining them through "endo" efforts. Traditional marketing practices have always been just about controlling and focusing on the "endo", however success today requires carefully managed and planned "exo" efforts as well.
In last week's NYT Sunday Magazine, Rob Walker went into some detail on some interesting "exo" approaches brands are taking to get word of mouth to happen.
the hidden (in plain sight) persuaders(requires purchase)
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