ivreg2.def

 x y z1 z2 
  
  Obs:   500 observations artificially generated



    Variable |       Obs        Mean    Std. Dev.       Min        Max
-------------+--------------------------------------------------------
           x |       500    .0289567    1.441686   -4.43988    4.32846
           y |       500    3.060344    2.229646   -3.57632   10.16687
          z1 |       500   -.0004661    1.010363   -2.82281     3.1517
          z2 |       500   -.0442213    1.011584   -3.18806    3.19265