Find combined mean and variance of two series | Function to find mean of series . ; Function to find the standard deviation of series . ; Function to find combined variance of two different series . ; mean1 and mean2 are the mean of two arrays . ; sd1 and sd2 are the standard deviation of two array . ; combinedMean is variable to store the combined mean of both array . ; d1_square and d2_square are the combined mean deviation . ; combinedVar is variable to store combined variance of both array . ; Driver code ; Function call to combined mean .
function mean ( arr , n ) { var sum = 0 ; for ( var i = 0 ; i < n ; i ++ ) sum = sum + arr [ i ] ; var mean = sum / n ; return mean ; } function sd ( arr , n ) { var sum = 0 ; for ( var i = 0 ; i < n ; i ++ ) sum = sum + ( arr [ i ] - mean ( arr , n ) ) * ( arr [ i ] - mean ( arr , n ) ) ; var sdd = sum / n ; return sdd ; } function combinedVariance ( arr1 , arr2 , n , m ) { var mean1 = mean ( arr1 , n ) ; var mean2 = mean ( arr2 , m ) ; document . write ( " " + mean1 . toFixed ( 4 ) + " " ) ; document . write ( " " + mean2 + " " ) ; var sd1 = sd ( arr1 , n ) ; var sd2 = sd ( arr2 , m ) ; document . write ( " " + sd1 . toFixed ( 3 ) + " " ) ; document . write ( " " + sd2 + " " + " " ) ; var combinedMean = ( n * mean1 + m * mean2 ) / ( n + m ) ; document . write ( " " + combinedMean . toFixed ( 4 ) + " " + " " ) ; var d1_square = ( mean1 - combinedMean ) * ( mean1 - combinedMean ) ; var d2_square = ( mean2 - combinedMean ) * ( mean2 - combinedMean ) ; document . write ( " " + d1_square . toFixed ( 3 ) + " " ) ; document . write ( " " + d2_square . toFixed ( 4 ) + " " ) ; var combinedVar = ( n * ( sd1 + d1_square ) + m * ( sd2 + d2_square ) ) / ( n + m ) ; return combinedVar ; } var arr1 = [ 23 , 45 , 34 , 78 , 12 , 76 , 34 ] var arr2 = [ 65 , 67 , 34 , 23 , 45 ] var n = arr1 . length ; var m = arr2 . length ; document . write ( " " + combinedVariance ( arr1 , arr2 , n , m ) . toFixed ( 3 ) ) ;