title: Use pairwise_tukeyhsd compare for all or multiple groups(more than 2)
body: <p>I have a dataset where I need to perform Tukey_test on multiple variables instead of pair-wise comparison:</p>
  
  <p>My data looks like:</p>
  
  <pre><code>Subject    State     Type   Success
     A        AZ        1        0.89
     B        TX        2        0.91
     C        NJ        3        0.78
     A        OH        4        0.91
  </code></pre>
  
  <p>My code:</p>
  
  <pre><code>from statsmodels.stats.multicomp import pairwise_tukeyhsd
  from statsmodels.formula.api import ols
  from statsmodels.base.model import Model
  
  p1_tukey_test = pairwise_tukeyhsd(data["Success"], data["Subject"] )
  f.write("\n\n" + str(p1_tukey_test._results_table))
  </code></pre>
  
  <p>My output:</p>
  
  <pre><code>  ===================================================================
    group1        group2         meandiff     lower      upper     reject
     ---------------------------------------------------------------------
      A              B            13.8883      12.493    15.2835   True 
      A              C            10.2884      8.5795    11.9972   True 
  </code></pre>
  
  <p>I want to have the output be like:</p>
  
  <pre><code>===================================================================
    group1        group2  group3       meandiff     lower      upper     reject
     ---------------------------------------------------------------------
   A               B        C            13.8883     12.493    15.2835   True
  </code></pre>
  
  <p>In other words , I dont want to have pairwise comparison rather I want to compare overall results for each category of Subject variable   </p>