演講摘要 : We investigate the decisions of whether and when to start consuming an addictive substance and examine the interdependence of the decisions for both legal and illegal substances. We first explore the onset and interdependence of substance uses by using a multivariate probit model. We then develop a multivariate split population duration model to deal with the onset, timing, and interdependence of substance uses. Our estimates suggest that there are strong cohort effects in substance uses. In addition, the cohort effect on the onset of substance use is distinctively different from that on the timing of the onset. We find that there is strong interdependence in the onset and timing of substance uses.
