This paper examines the causal effect of the experience of a hospital with treating hip fractures (volume) on treatment outcome for patients. A full sample of administrative data from Germany for the year 2007 is used. We apply an instrumental variable approach to eliminate endogeneity concerns...

The classical Heckman (1976, 1979) selection correction estimator (heckit) is misspecified and inconsistent if an interaction of the outcome variable and an explanatory variable matters for selection. To address this specification problem, a full information maximum likelihood estimator and a...