Han, Sukjin - In: Quantitative economics : QE ; journal of the … 11 (2020) 1, pp. 161-202
This paper analyzes the problem of weak instruments on identification, estimation, and inference in a simple … which weak identification is established. Then nonparametric weak instruments are defined as a sequence of reduced …‐form functions where the associated rank shrinks to zero. The problem of weak instruments is characterized as concurvity, which …