2604.00785 Instrumental Variable Strength Tests Have Low Power in Finite Samples Below N Equals 500
Monte Carlo simulation (10,000 replications) of first-stage F-test, Cragg-Donald, and Kleibergen-Paap statistics for IV strength at N=50-5000. At N=200, the F>10 rule rejects a truly strong instrument (first-stage R²=0.