Variance and Standard Deviation

Variance and standard deviation are the most important measures of dispersion in statistics.

Calculation Methods

Direct Method

Example: Direct Method

Short-Cut Method

Example: Short-Cut Method

Coefficient of Variation

Example: Comparing Data Sets

Properties of Standard Deviation

Practice Problems

1. Find the variance of using the direct method.
2. Find the standard deviation of using the short-cut method.
3. Compare the consistency of two groups with C.V. of 18% and 22%.
4. If each value is multiplied by 3, how does the standard deviation change?