Even the simple most data analysis requires application of statistical functions
such as finding the mean value of a collection of data.
Python standard library has several statistical functions builtin with it.
The statistical functions are available to the programmer through the python module statistics, which can be imported as given here.
import statistics 
The module statistics provides two types of functions.
 A set of functions to find where the data is centered around in a distribution  i.e, Functions to find the measures of central tendencies. e.g., Mean(), Median(), Mode
 A set of functions to find how the data is dispersed, meaning how the data is dispersed from the central values. e.g., pvariance(), pstdev() which find the variance and the standard deviation of the distribution.
List of statistical functions to find the measures of central tendency
Finds and returns the Arithmetic Mean of the data, popularly called as the average value of the data. 

Returns the harmonic mean also called as the subcontrary mean of the data 

Returns the median value, which is the middle value of the distribution. 

median_low() 
Returns the low median value of the distribution 
median_high() 
Returns the high median of the distribution 
median_grouped() 
Median of the grouped data will be returned. 
Returns the most occurring value of the distribution, which is called as the mode of the distribution. 
List of statistical functions to find the measures of dispersion
Returns the standard deviation of the population data 

Returns the standard deviation the sample data 

Returns the variance of the population data 

Returns the variance of the sample data 