We study asymptotic inference based on cluster-robust variance estimators for regression models with clustered errors, focusing on the wild cluster bootstrap and the ordinary wild bootstrap. We state conditions under which both asymptotic and bootstrap tests and confidence intervals will be...

This article discusses estimates of variance for two-stage models. We present the sandwich estimate of variance as an alternative to the Murphy-Topel estimate. The sandwich estimator has a simple formula that is similar to the formula for the Murphy ÐTopel estimator,and the two estimators are...