Method: Wonkavision::Plugins::Aggregation::Measure#std_dev

Defined in:
lib/wonkavision/plugins/analytics/aggregation/measure.rb

#std_dev ⇒ Object

Calculate the standard deviation



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# File 'lib/wonkavision/plugins/analytics/aggregation/measure.rb', line 143

def std_dev
  return Wonkavision::NaN unless @count > 1
  Math.sqrt((@sum2.to_f - ((@sum.to_f * @sum.to_f)/@count.to_f)) / (@count.to_f - 1))
end