Find Sample Variance Using Python

Sample Variance:

Sample variance is a statistic, which measures the dispersion in a Sample.

Sample variance is used as an estimator of the population variance.

Sample variance s2 is given by the formula

s2 = i(1 to n)(xi-)2/n-1


The reason the denominator has n-1 instead of n is because usage of n

in the denominator underestimates the population variance. Using n-1 makes the Sample Variance an unbiased estimator of the Population Variance.


Method Name:



Method Overview:

The variance() function takes a sequence or an iterator as the parameter containing the sample data and returns the sample variance.



Python raises a StatisticsError if the data passed inside the variance() is empty


Python Example Program to find sample variance:


# import the statistics module

import statistics


sampleData = [55,56,54,53,52,67,56,62,59]


sampleVariance = statistics.variance(sampleData)


print("Sample variance of the distribution is %.2f"%(sampleVariance))



Example Python program output that finds the sample variance:


Sample variance of the distribution is 23.11


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