Step 1: Find the mean of the values of the data set.
Step 2: Find the difference between the mean and each separate value of the data set.
Step 3: Square each difference found in step 2.
Step 4: Add up all of the squared values found in step 3.
Step 5: Divide the sum found in step 4 by the number of data values in the set.
Step 6: Find the nonnegative square root of the quotient found in step 5.