# Measuring Spread of Distributions ## Measuring Spread ## Variance $Var=\frac{1}{n}\sum^{n}_{i=1}(x_i - \mu)^2$ ## Covariance ## Standard Deviation 1. Work out the mean of the numbers. 2. For each number, subtract the mean and square the result. 3. Find the mean of those square differences. 4. Take the square root of that mean. $Sd=\sqrt{\frac{1}{n}\sum^{n}_{i=1}(x_i - \mu)^2}$ --- - [ ] z-score $Z=\frac{x-\mu}{\sigma}$