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-x̄)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:
variance(data)
Method Overview:
The variance() function takes a sequence or an iterator as the parameter containing the sample data and returns the sample variance.
Exceptions:
Python raises a StatisticsError if the data passed inside the variance() is empty
Python Example Program to find sample variance:
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# 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))
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Example Python program output that finds the sample variance:
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Sample variance of the distribution is 23.11 |