The following features have been added to the HPPANEL procedure:
the between-groups estimator, which is equivalent to regression on cross-sectional means (to obtain this estimator, specify the BTWNG option in the MODEL statement)
the between-time-periods estimator, which is equivalent to regression on means at each time point (to obtain this estimator, specify the BTWNT option in the MODEL statement)
pooled OLS regression, which is obtained by specifying the POOLED option in the MODEL statement