用 median。

median performs a nonparametric K-sample test on the equality of medians.  It tests the null hypothesis that the K samples were drawn from populations with the same median.  In the case of two samples, the test chi-squared statistic is calculated both with and without a continuity correction.

median varname [if] [in] [weight], by(groupvar) [median_options]

median_options

    * by(groupvar)         grouping variable
      exact                performs Fisher's exact test
      medianties(below)    assign values equal to the median to below group
      medianties(above)    assign values equal to the median to above group
      medianties(drop)     drop values equal to the median from the analysis
      medianties(split)    split values equal to the median equally between the two groups