question: @ Override public double variance ( double totalWeight , double totalPositiveWeight , Hypothesis hypo ) { double fp = hypo . getCoveredWeight ( ) - hypo . getPositiveWeight ( ) ; double tn = totalWeight - totalPositiveWeight - fp ; double correctPredictions = hypo . getPositiveWeight ( ) + tn ; double mean = correctPredictions / totalWeight ; double innerTerm = correctPredictions * Math . pow ( 1.0d - mean , 2 ) + ( totalWeight - correctPredictions ) * Math . pow ( 0.0d - mean , 2 ) ; return Math . sqrt ( innerTerm ) / totalWeight ; }
target:  Calculates the empirical variance. 