“Which book should I buy?”

A guy called Jared Spool studied how people make that choice.

Spool, a usability expert who lectures around the world, studied people browsing through bookstores.  Observing how people determine what a book is about, Spool found that approximately half turn to the back of the book and review the index.  More here.

“Which book is worthy of my time?” is a variation on this theme.  That question has also been answered by reviewing the index.  More here.