This was more a correlation than causation (see Freakonomics for a description). Typically, families that can't afford books have other general issues that prec

This was more a correlation than causation (see Freakonomics for a description). Typically, families that can't afford books have other general issues that preclude their children from doing well (for example, they are poor, their parents typically work more than 1 job and can't spend much time with their children, etc).