“Analyzing the available data about AA requires that we begin with a clear definition of success. Success, after all, can mean any number of things. Should one measure it in days of sobriety? Weeks without a binge episode? What if people who are making substantive progress slip and have one drink during an otherwise successful period of time: Should they “go back to zero,” as is the practice in many AA chapters? What if they stop drinking but acquire a gambling problem instead?”