We explore five youth risky behaviors: alcohol usage, marijuana usage, cocaine usage, sex activity, and delinquency. The first four behaviors are measured by age of initiation. Age when started a risky behavior was asked in multiple waves of interviews. In general, the value usually taken was from the earliest year the question was asked. However, to overcome potential data entry errors, if the reported age of initiation is less than 11, then a later year entry was taken. Those who reported age of initiation less than 11 were included in the youngest age group. Age when started to use alcohol was asked in both the 1982 and the 1983 interview. Age of marijuana and cocaine initiation was created using the 1984 and 1998 questions on drug initiation. Age of sex initiation was created using the 1983, 1984, and 1985 questions on sex initiation. Age of initiation is grouped into four categories: 11-15, 16-17, 18-19, and not by age 19 (i.e. after age 19 or never initiated).
Delinquency was measured as the total number of delinquent and/or criminal acts reported in the 1980 interview. The 1980 NLSY9 included a self-reported section detailing respondents' participation in and income from delinquent or criminal activities such as skipping school, alcohol/marijuana use, vandalism, shoplifting, drug dealing, robbery, assault, or gambling during the previous twelve-month period. Alcohol and drug use were not included so as not to double-count with the other risky behavior measures. Measures of the total number of delinquent/criminal acts and the types of delinquent/criminal acts were both created. Since distributions of both measures are very similar, we opt to use only the first measure. This measure could be problematic because of the age differences among respondents in 1980. However, the chosen measure predicted very well the likelihood of spending time in jail. Further research could be considered to separate personal versus property crimes, frequently distinguished in the criminal behavior literature. The number of delinquent/criminal activities was grouped into four categories: no delinquent/criminal acts, 1-2, 3-8, and 9 or more.