code: def fstat_to_wellek(f_stat, n_groups, nobs_mean):
      """Convert F statistic to wellek's effect size eps squared
  
      This computes the following effect size :
  
         es = f_stat * (n_groups - 1) / nobs_mean
  
      Parameters
      ----------
      f_stat : float or ndarray
          Test statistic of an F-test.
      n_groups : int
          Number of groups in oneway comparison
      nobs_mean : float or ndarray
          Average number of observations across groups.
  
      Returns
      -------
      eps : float or ndarray
          Wellek's effect size used in anova equivalence test
  
      """
      es = f_stat * (n_groups - 1) / nobs_mean
      return es
  
imports: import numpy
  from scipy import stats
  from scipy.special import ncfdtrinc
  from statsmodels.stats.power import ncf_cdf, ncf_ppf
  from statsmodels.stats.robust_compare import TrimmedMean, scale_transform
  from statsmodels.tools.testing import Holder
  from statsmodels.stats.base import HolderTuple
label_desc: Use image node_id 6 for calling a global function with example usage: fstat_to_wellek(f_stat, n_groups, nobs_mean) and returns: es