The NLSY79 offers us a set of risky behaviors that typically begin during or near the teenage years, if they begin at all. We examine five of these behaviors:
- alcohol usage,
- marijuana usage,
- cocaine usage,
- sexual activity, and
Each of these is measured using age of initiation except for delinquency, which is a measure of total number of delinquent and/or criminal acts in 1980. We divide ages of initiation into four age categories:
- 11-15 (early adolescence);
- 16-17 (middle adolescence);
- 18-19 (late adolescence); and
- those who did not initiate as an adolescent (either initiated after age 19 or never initiated).
Combining those who initiate after age 19 and those who never initiate reflects our interest in the effects of adolescent behavior. These two groups include all individuals who did not initiate as an adolescent. Further, since we do not observe respondents' entire lifetimes, we cannot know if they "never" initiate. One caveat throughout our analysis is that "late initiators" and "never initiators" may be very different groups.
Two primary ways of analyzing delinquency appear in the literature. One divides delinquent acts into "personal" and "property" (e.g. Greenberg 1985). Another common method is to break down delinquency by levels of frequency. Nye and Short (1957) suggest four categories: (1) did not commit the act, (2) committed the act once or twice, (3) committed the act several times, and (4) committed the act very often. We adopt this latter approach and define four categories of delinquency based on the number of delinquent/criminal acts engaged in: 0, 1-2, 3-8, and 9 or more.