Some general insights: The longer a mystery novel is, the more likely readers are to jump to the end to see who done it. People are more likely to finish biographies than business titles, but a chapter of a yoga book is all they need. They speed through romances faster than religious titles, and erotica fastest of all.
[Other] data shows that readers are 25 percent more likely to finish books that are broken up into shorter chapters. That is an inevitable consequence of people reading in short sessions during the day on an iPhone.
–Google Analytics-like stats, coming soon for ebooks.