X is Laplace No leverage correction Three distributions for X: Normal, uniform, Laplace Inference for the slope in simple linear parametric regression Actual coverage probabilities of a nominal 95% confidence interval. Leverage corrections means we correct residuals for leverage degrees of freedom means we correct sandwich estimator of variance by multiplication by n/df, and use t--percentiles with this df. Overdispersion means the variance of the t--statistic reletive to the variance of a t--random variable with n-2 degrees of freedom Degrees of freedom Over-- Sample n n-1 n-2 n-3 n-4 n-5 Dispersion Size 0.8264 0.8466 0.8680 0.8926 0.9196 0.9464 2.530 10.00 0.8322 0.8490 0.8696 0.8920 0.9142 0.9364 2.551 11.00 0.8504 0.8680 0.8844 0.9030 0.9230 0.9398 2.110 12.00 0.8444 0.8626 0.8788 0.8952 0.9134 0.9312 2.179 13.00 0.8598 0.8756 0.8894 0.9034 0.9196 0.9342 1.950 14.00 0.8578 0.8738 0.8862 0.8998 0.9132 0.9270 1.983 15.00 0.8676 0.8778 0.8876 0.9002 0.9124 0.9240 1.890 16.00 0.8702 0.8800 0.8920 0.9034 0.9132 0.9236 1.892 17.00 0.8724 0.8806 0.8894 0.8990 0.9102 0.9230 1.836 18.00 0.8724 0.8822 0.8906 0.9014 0.9106 0.9196 1.812 19.00 0.8856 0.8924 0.9004 0.9106 0.9182 0.9278 1.681 20.00 0.8916 0.9006 0.9072 0.9136 0.9228 0.9326 1.604 21.00 0.8840 0.8912 0.9002 0.9068 0.9146 0.9226 1.634 22.00 0.8960 0.9054 0.9122 0.9186 0.9264 0.9324 1.498 23.00 0.8908 0.8974 0.9078 0.9150 0.9214 0.9260 1.582 24.00 0.8854 0.8916 0.8990 0.9056 0.9122 0.9192 1.606 25.00 0.9016 0.9080 0.9130 0.9190 0.9252 0.9298 1.509 26.00 0.8980 0.9058 0.9100 0.9148 0.9204 0.9256 1.491 27.00 0.8962 0.9030 0.9066 0.9130 0.9170 0.9228 1.518 28.00 0.9030 0.9096 0.9150 0.9208 0.9248 0.9330 1.469 29.00 0.9050 0.9096 0.9128 0.9174 0.9232 0.9290 1.460 30.00