How to calculate the variance and the standard deviation of data using Python?

by Amrita Mitra | Feb 9, 2023 | Statistics For Machine Learning

Calculate Variance And Standard Deviation In Python

True Variance:  6.640000000000001
Sample Variance:  7.377777777777778
True Standard Deviation:  2.5768197453450252
Sample Standard Deviation:  2.716206504995115

Please note that the numpy.var() and numpy.std() functions take ddof as an argument. This ddof indicates the delta degrees of freedom and it is used to calculate the variance and standard deviation. By default, ddof = 0 and the numpy.var() and numpy.std() functions calculate the true variance and true standard deviation, respectively.

When we give ddof = 1 as input, the functions use (n – 1) as the denominator while calculating the variance and the standard deviation. Thus, to calculate the sample variance and sample standard deviation of data using the numpy module, we need to provide ddof = 1 as argument to the numpy.var() and numpy.std() functions, respectively.

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