We develop results for the use of LASSO and Post-LASSO methods to form first-stage predictions and estimate optimal instruments in linear instrumental variables (IV) models with many instruments, p, that apply even when p is much larger than the sample size, n. We rigorously develop asymptotic...

It is well known that homeowners are richer than renters, even after controlling for observable characteristics. This is often used as an argument for policies that foster homeownership. However, the causal link between homeownership and wealth is difficult to establish due to many potential...

We evaluate the impacts of a compulsory dialogue meeting for long-term sick-listed workers in Norway. The meeting is organised by the local social security administration after around six months of absence, and its purpose is to bring together the absentee, the employer, and the family physician...

Highly non-elliptical posterior distributions may occur in several econometric models, in particular, when the likelihood information is allowed to dominate and data information is weak. We explain the issue of highly non-elliptical posteriors in a model for the effect of education on income...

Education is argued to be an important driver of the decision to start a business. The measurement of its influence, however, is difficult since it is considered to be an endogenous variable. This study accounts for this endogeneity by using an instrumental variables approachand a data set of...

This paper considers the finite sample distribution of the 2SLS estimator and derives bounds on its exact bias in the presence of weak and/or many instruments. We then contrast the behavior of the exact bias expressions and the asymptotic expansions currently popular in the literature, including...

We provide simple tests for selection on unobserved variables in the Vytlacil-Imbens-Angrist framework for Local Average Treatment Effects. The tests allow researchers not only to test for selection on either or both of the treated and untreated outcomes, but also to assess the magnitude of the...

This paper examines a general class of inferential problems in semiparametric and nonparametric models defined by conditional moment restrictions. We construct tests for the hypothesis that at least one element of the identified set satisfies a conjectured (Banach space) "equality" and/or (a...

This paper develops characterizations of identified sets of structures and structural features for complete and incomplete models involving continuous and/or discrete variables. Multiple values of unobserved variables can be associated with particular combinations of observed variables. This can...