“Most of the publishers did not want to be identified, to avoid alarming their authors.”

A company called Jellybooks is tracking reader behavior on e-books, The New York Times reports:

On average, fewer than half of the books tested were finished by a majority of readers. Most readers typically give up on a book in the early chapters. Women tend to quit after 50 to 100 pages, men after 30 to 50. Only 5 percent of the books Jellybooks tested were completed by more than 75 percent of readers. Sixty percent of books fell into a range where 25 percent to 50 percent of test readers finished them. Business books have surprisingly low completion rates.

How Will Publishers Use the Data?

For the most part, the publishers who are working with Jellybooks are not using the data to radically reshape books to make them more enticing, though they might do that eventually. But some are using the findings to shape their marketing plans. For example, one European publisher reduced its marketing budget for a book it had paid a lot of money to acquire after learning that 90 percent of readers gave up after only five chapters. A German publisher decided to increase advertising and marketing on a debut crime novel after data showed that nearly 70 percent of readers finished it.

Publishers might also use the data to learn what type of reader a book appeals to, and market it accordingly. One of the novels that Jellybooks tested was written for teenagers but proved surprisingly popular with adults.
Why This Is Scary for Authors

Authors are understandably nervous about how new insights into reading behavior might shape publishers’ editorial decisions. Suppose you are writing a crime series, and readers gave up halfway through the latest installment. Publishers might not want to buy the next one. Or what if readers skip around in your nonfiction book, a common way to read nonfiction? An editor might want to cut the chapters people are skipping, potentially erasing useful context.

And, of course, people who sign up for a free e-book service might not represent the kinds of readers who would seek and pay for a crime novel, or a nonfiction book on a subject that interests them. The sample sizes are relatively small. So the reader data might not represent the reactions of a general audience.

Why This Might Be Troubling for Readers

Jellybooks users consent to having their data tracked in exchange for free books, and must click on a link to send that data to Jellybooks. “It’s absolutely critical to have the user in control, or we face a backlash,” Mr. Rhomberg said at the conference.

But as the book industry gets more sophisticated about how to measure reading behavior and the practice becomes more widespread, real privacy concerns could emerge. Some big academic publishers already track how students read their e-books, and some e-book subscription services have developed the capacity to measure reader engagement. Regular e-book readers might not realize that digital retailers are recording and storing the data. A few years ago, California instituted the “reader privacy act,” which made it harder for law enforcement agencies to collect information on consumers’ digital reading records from e-book retailers. But most other states have not taken such steps...