. use murder96

. summarize tot gun nogun

Variable |     Obs        Mean   Std. Dev.       Min        Max
---------+-----------------------------------------------------
     tot |      28    802.6071   86.48243        660        970  
     gun |      26    517.7308    96.2524        374        692  
   nogun |      26    284.6538   29.95055        220        331  

. cor tot gun nogun, cov
(obs=26)

        |      tot      gun    nogun
--------+---------------------------
     tot|  8043.21
     gun|  8205.35  9264.52
   nogun| -162.142 -1059.18  897.035


. display 8043.21 / 802.6071, invchi(27,.05), invchi(27,.05)/27
10.021354 40.11327 1.4856767

. di 9264.52/517.7308, invchi(25,.05)
17.894473 37.652493

. di 897.035/284.6538, invchi(25,.05)
3.1513193 37.652493