We provide an overidentification test for a nonparametric treatment model where individuals are allowed to select into treatment based on unobserved gains. Our test can be used to test the validity of instruments in a framework with essential heterogeneity (Imbens and Angrist 1994). The...

This paper studies the effect of attending a high-quality secondary school on subsequent educational outcomes. The analysis is based on data from the German Socio-Economic Panel Study in which we observe children when they make their secondary school choice (between ages 10-12) and later when...

This paper examines the causal effect of volume on outcome on the example of patients with a hip fracture. We use an instrumental variable approach and consider both the practice-makes-perfect and selective-referral hypothesis as well as unobserved patient heterogeneity. Our results indicate...

Does immigration accelerate sectoral change towards high-productivity sectors? This paper uses the mass displacement of ethnic Germans from Eastern Europe to West Germany after World War II as a natural experiment to study this question. A simple two-sector specific factors model, in which...

This study attempted to analyze the effect of regulation and political stability in allocation of mobile telecommunication investments in the African continent between year 2001 and 2011. In order to better understand the dynamics of investment in telecommunications, a framework was developed to...