Scores were summed across two items at each wave: “During the past 3 months, how many times did you have sex without protection against STDs and pregnancy with an [exclusive/non-exclusive] dating partner?” We included both exclusive and non-exclusive unprotected sex because being in a reportedly exclusive relationship is not necessarily protective against sexually transmitted infections or unintended pregnancy. These two questions had the following choices: 0 = 0 times, 1 = 1 time, 2 = 2 times, 3 = 3–5 times, 4 = 6–10 times, 5 = 11–20 times, 6 = >20 times.
