[Update: I've posted additional analysis from the MIT team here] One of the most quoted statistics in my original article was the data point that 57% of Amazon’s book sales are in the Long Tail, defined as beyond the 100,000 books available in the typical Barnes and Noble superstore (we sometimes used 130,000, which is the inventory of its larger stores). We arrived at that number by working with
![A methodology for estimating Amazon's Long Tail sales](https://cdn-ak-scissors.b.st-hatena.com/image/square/4e50fff25f86d89327f34089f6deb51a1b23f4fa/height=288;version=1;width=512/http%3A%2F%2Flongtail.typepad.com%2Fthe_long_tail%2Fimages%2Famazon.jpg)