That football Head Coaches will be dismissed for poor performance and will quit when they have better outside options seems to be nothing more than a statement of the obvious. But owners may find it hard to distinguish poor performance from bad luck and may find it difficult to identify and...

We establish nonparametric identification in a class of so-called index models using a novel approach that relies on general topological results. Our proof strategy imposes very weak smoothness conditions on the functions to be identified and does not require any large support conditions on the...