Square root of the mean square value of a random variable. In otherwords, we can define the root mean square is a statistical measure of the magnitude of a varying quantity. It can be calculated for a series of discrete values or for a continuously varying function. It is also known as Quadratic Mean(QM).
X = Individual score N = Sample size (Number of scores)
To find the Root Mean Square of -2,-1,-3,1,5.
Count the total number of values. N = 5
Square all the values. 4,1,9,1,25
Take the average of the square values. 4+1+9+1+25/5 = 40/5 = 8
Take the square root of the average values. RMS/QM = sqrt(8) = 2.83 This example will guide you to calculate the Root mean square/Quadratic Mean manually.
This tutorial will help you dynamically to find the Root Mean Square(RMS)/Quadratic Mean(QM) problems.