[no subject]

[Sarah Elaine Cabbage <cabbages@u.washington.edu>]

Hello,

I'm trying to do a permutation test in Stata and just can't seem to 
get the syntax right.  Here's my command:

permute norm_qty  permt=r(t), strata(group) : ttest norm_qty, 
by(group)

This is what I get in return:


Monte Carlo permutation results

Number of strata =          2                  Number of obs   =       10

      command:  ttest norm_qty, by(group)
        permt:  r(t)
  permute var:  norm_qty

------------------------------------------------------------------------------
T            |     T(obs)       c       n   p=c/n   SE(p) [95% Conf.Interval]
-------------+----------------------------------------------------------------
       permt |  -4.373186     100     100  1.0000  0.0000  .9637833        1
------------------------------------------------------------------------------
Note:  Confidence interval is with respect to p=c/n.
Note:  c = #{|T| >= |T(obs)|}


I'm trying to do a comparison of mean values of "norm_qty" between two 
groups with a small sample size.  Why is it telling me that all my
permutations come out with the same T-statistic as the observed 
distribution?

Thank you very much for any help anyone can give me.


Sarah Cabbage
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