While millions of readers happily plow through the latest novel on their favorite e-readers, few have any idea just how much data their devices are collecting about them. For the first time, publishers and authors are getting hold of big data about how people read, and while it can be used to help write more crowd-pleasing novels, groups like the EFF are concerned for readers’ privacy. The Wall Street Journal takes a look at the rise of e-readers, and how the data they unearth is changing the conventional publishing model, telling us more about how we consume books, and pressuring a shift toward focus group-driven storytelling.