Valid t-Ratio Inference for IVt

In the single-IV model, researchers commonly rely on t-ratio-based inference, even though the literature has quantified its potentially severe large-sample distortions. Building on Stock and Yogo (2005), we introduce the tF critical value function, leading to a stan-dard error adjustment that is a smooth function of the first-stage F-statistic. For one-quarter of specifications in 61 AER papers, cor-rected standard errors are at least 49 and 136 percent larger than conventional 2SLS standard errors at the 5 percent and 1 percent significance levels, respectively. tF confidence intervals have shorter expected length than those of Anderson and Rubin (1949), whenever both are bounded. (JEL C13, C26)