Sample variance is a measure of how far each value in the data set is from the sample mean.

**Formula to calculate sample variance.**

To calculate sample variance;

- Calculate the mean( x̅ ) of the sample
- Subtract the mean from each of the numbers (x), square the difference and find their sum.
- Divide the result by total number of observations (n) minus 1.

**Example:**

Determine the variance of the following sample data.

2, 5, 6, 1

We begin by finding the mean of the sample data.

Then subtract the mean from each of the numbers, square the difference and find their sum.

Divide the result by the total number of observations minus one.