Published Review of Economic Studies Online 30 Dec 2025 Published Sep 2026A Robust Test for Weak Instruments for 2SLS with Multiple Endogenous RegressorsDaniel J Lewis · Karel MertensThis paper develops a test for instrument strength based on the bias of two-stage least squares (2SLS) that: (1) generalizes the Stock-Yogo (2005) and Sanderson-Windmeijer (2016) tests to be robust to …