Calculate variance by finding the average of the square of the data values' differences from the mean. You need the data values, mean, squared mean difference and the number of data values in the data set.
Continue ReadingDetermine the values of each of the items in the data set.
Calculate the mean of the data values by dividing their summation by the number of data values in the data set. If the data set is a, b, c, d, e, then the mean is (a + b + c +d + e)/5 since there are five data values in the set.
Calculate the mean differences by subtracting the mean from each data value. If the mean is m, then the mean differences are a - m, b - m, c - m, d - m and e - m.
Multiply each square difference by itself. For the mean differences a - m, b - m, c - m, d - m and e - m, then the squared differences are (a - m)2, (b - m)2, (c - m)2, (d - m)2,and (e - m)2.
Find the average of the squared differences by dividing their summation by the number of data values. For the squared differences (a - m)2, (b - m)2, (c - m)2, (d - m)2,and (e - m)2, the variance is [(a - m) 2 + (b - m) 2+ (c - m) 2 + (d - m) 2 + (e - m) 2]/5.