Method: Statsample::StratifiedSample.variance_esd_wr

Defined in:
lib/statsample/multiset.rb

.variance_esd_wr(es) ⇒ Object

Based on stattrek.com/Lesson6/STRAnalysis.aspx



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# File 'lib/statsample/multiset.rb', line 152

def variance_esd_wr(es)
  n_total=calculate_n_total(es)
    sum=es.inject(0){|a,h|
      val= ((h['s']**2 * h['N']**2) / h['n'].to_f)
      a+val
    }
    (1.0/(n_total**2))*sum
end