The greater the variability spread of the distribution the greater the deviations from the mean ignoring the signs of the deviation. Work out the Mean the simple average of the numbers Then for each number. Variance is the average of squared differences of data from mean.
Just as in the section on central tendency where we discussed measures of the center of a distribution of scores in this chapter we will discuss measures of the variability of a distribution.
An introduction to measures of variability. If you want to calculate the variance of a probability distribution you need to calculate E X 2 - E X 2. In the example the square root of 266667 equals approximately 5164. Let Varx denote the variance of a set of numbers.