thread: 2009-10-27 : Book Publishing - Some Startling Numbers
On 2009-10-27, Jono wrote:
Sounds like book sales must be a power-law distribution: the top 20% of the books account for 80% of all sales, and then the graph has a long, long tail comprising a semi-infinite number of books selling practically nothing.
Here's the thing: all of our intuition about what "average" means is based on bell-curve-shaped "normal" distributions, where the mean, median, and mode are all the same number. Intuition about averages is extremely misleading when applied to power-law distributions, where the mean, median, and mode are very different. For example, "the average book sells 250 copies/yr" makes it sound like half sell more and half sell less, but actually it means nearly all books sell less than that, while only a few Harry Potters and Da Vinci Codes sell more.
Power-law distributions are seen in everything from blog readership to the size of earthquakes to the session lifespans of web-browser tabs (my field). So this isn't some weird quirk of book publishing - it's nearly a law of nature. The numbers sound shockingly low, but actually they're exactly what we should expect due to the power-law distribution.
The "falling fast" part is still pretty worrisome, though.
Oh, and I just ordered a copy of In A Wicked Age, so, um, add +1?
