1 Nonparametric bounds on the causal effect of university studies on job opportunities using principal stratification Leonardo Grilli Fabrizia Mealli University of Florence Summary. The paper proposes a methodology, based on the principal strata approach to causal inference, for assessing the relative effectiveness of two degree programmes with respect to the employment status of their graduates. An innovative use of nonparametric bounds in the principal strata framework is shown, examining the role of some assumptions in reducing the uncertainty about the causal effects, and proposing a strategy to employ the covariates in the construction of the bounds. In the application, the nonparametric bounds turn out to be quite informative on the average causal effect for the latent group of students who are potentially able to graduate in both degree programmes. There is some evidence that the effect is positive for Economics with respect to Political Science, at least for some values of the covariates. Keywords: bounds, causal effects, effectiveness, potential outcomes, principal strata. Traditional analyses of the effect of degree programmes on the employment status (an example of external effectiveness) are performed on the sole basis of graduated students, Draft of the paper Grilli L. & Mealli F. (2008) Nonparametric Bounds on the Causal Effect of University Studies on Job Opportunities Using Principal Stratification. Journal of Educational and Behavioral Statistics, 33(1), pp 111-130 DOI: 10.3102/1076998607302627 http://jeb.sagepub.com/content/33/1/111.abstract