\begin{tabular}{*{2}{l}}
\hline
                  & M1   \tabularnewline
                   &Estimate \tabularnewline
                 &(S.E.) \tabularnewline
 \hline
 \hline
   (Intercept)     &-424.260 \tabularnewline
                 &(379.001)  \tabularnewline
   x1              &6.523 \tabularnewline
                 &(  7.209)  \tabularnewline
   x2              &7.355 \tabularnewline
                 &(  7.362)  \tabularnewline
   x1:x2           &0.392** \tabularnewline
                 &(  0.139)  \tabularnewline
 \hline
 N                 &400       \tabularnewline
 RMSE             &257.191   \tabularnewline
 $R^2$             &0.703   \tabularnewline
 adj $R^2$         &0.701   \tabularnewline
 \hline
\hline
 
 \multicolumn{2}{c}{${*  p}\le 0.05$${*\!\!*  p}\le 0.01$${*\!\!*\!\!*  p}\le 0.001$}\tabularnewline
 \end{tabular}