Find the mean: add all values and divide by the number of values
Subtract the mean from each value
Square each result
Add all the squared results
Divide by the number of values for population variance
Divide by the number of values minus 1 for sample variance
Use the formula: variance = Σ(x – mean)² / N
Use the formula: sample variance = Σ(x – mean)² / (n – 1)