code: def ltiecorrect(rankvals):
      
      sorted,posn = shellsort(rankvals)
      n = len(sorted)
      T = 0.0
      i = 0
      while (i<n-1):
          if sorted[i] == sorted[i+1]:
              nties = 1
              while (i<n-1) and (sorted[i] == sorted[i+1]):
                  nties = nties +1
                  i = i +1
              T = T + nties**3 - nties
          i = i+1
      T = T / float(n**3-n)
      return 1.0 - T
docs: Corrects for ties in Mann Whitney U and Kruskal Wallis H tests.  See
  Siegel, S. (1956) Nonparametric Statistics for the Behavioral Sciences.
  New York: McGraw-Hill.  Code adapted from |Stat rankind.c code.
  
  Usage:   ltiecorrect(rankvals)
  Returns: T correction factor for U or H