The SAS System                           1

                  Obs    treatment    cold    count

                   1      placebo       1       31
                   2      placebo       0      109
                   3      ascorb        1       17
                   4      ascorb        0      122

                            The SAS System                           2

                         The TTEST Procedure

                           Variable:  cold

Frequency: count

  treatment      N      Mean   Std Dev   Std Err   Minimum   Maximum

  ascorb       139    0.1223    0.3288    0.0279         0    1.0000
  placebo      140    0.2214    0.4167    0.0352         0    1.0000
  Diff (1-2)         -0.0991    0.3755    0.0450

 treatment    Method              Mean      95% CL Mean       Std Dev

 ascorb                         0.1223     0.0672   0.1774     0.3288
 placebo                        0.2214     0.1518   0.2911     0.4167
 Diff (1-2)   Pooled           -0.0991    -0.1876  -0.0106     0.3755
 Diff (1-2)   Satterthwaite    -0.0991    -0.1876  -0.0107

            treatment    Method            95% CL Std Dev

            ascorb                         0.2942   0.3728
            placebo                        0.3729   0.4722
            Diff (1-2)   Pooled            0.3467   0.4096
            Diff (1-2)   Satterthwaite

     Method           Variances        DF    t Value    Pr > |t|

     Pooled           Equal           277      -2.20      0.0283
     Satterthwaite    Unequal      263.59      -2.21      0.0282

                        Equality of Variances

          Method      Num DF    Den DF    F Value    Pr > F

          Folded F       139       138       1.61    0.0056