Method: Statsample::StratifiedSample#standard_error_wor_2

Defined in:
lib/statsample/multiset.rb

#standard_error_wor_2(field) ⇒ Object

Standard error with estimated population variance and without replacement. Source: stattrek.com/Lesson6/STRAnalysis.aspx



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# File 'lib/statsample/multiset.rb', line 265

def standard_error_wor_2(field)
  sum=@ms.sum_field(field) {|s_name,vector|
    s_size=@strata_sizes[s_name]
  (s_size**2 * (1-(vector.size.to_f / s_size)) * vector.variance_sample / vector.size.to_f)
  }
  (1/@population_size.to_f)*Math::sqrt(sum)
end