is it possible to cluster errors can standard errors be clustered can you cluster standard errors in data can standard errors be clustered on time what variables cluster standard errors can a time variable be clustered can standard error be clustered can you cluster standard error on a time variable is it possible to cluster standard error on time variables is it possible to cluster standard errors on time variables? can you cluster standard error can you cluster errors on time variables how to cluster standard errors can we cluster standard error can you cluster standard error on time variables can you cluster errors how do you cluster standard errors can we cluster standard errors does time variable affect standard error can standard errors be clustered?