Hoderlein, Stefan; Holzmann, Hajo; Meister, Alexander - 2015
with random coefficients and exogenous regressors in both equations. We establish a profound non-identification result: the … joint distribution of the random coefficients is not identified, implying that counterfactual outcomes are also not … focus on means of random coefficients (implying that IV is generally biased), or let the instrument enter the first stage in …