 # Statistical Functions in Python | Set 2 (measure of distribution)

1. variance () : — this function calculates variance, i.e.  a measure of data bias, the larger the variance value, the more scattered the data values ​​. The sample variance is calculated in this function, assuming the data are for the population. If the passed argument is empty, StatisticsError is thrown.

2. pvariance () : — this function calculates the variance of the entire population . The data is interpreted as the entire population. If the passed argument is empty, StatisticsError is raised.

 ` # Python code to demonstrate how it works ` ` # variance () and pvariance () `   ` # import statistics for processing statistical operations ` ` import ` ` statistics `   ` # initializing list ` ` li ` ` = ` ` [` ` 1.5 ` ` , ` ` 2.5 ` `, ` ` 2.5 ` `, ` ` 3.5 ` `, ` ` 3 .5 ` `, ` ` 3.5 ` `] `   ` # using variance to calculate data variance ` ` print ` ` (` `" The variance of data is: "` `, end ` ` = ` ` "") ` ` print ` ` (statistics.variance (li)) `   ` # using pvariance to calculate variance of population data ` ` print ` ` (` ` "The population variance of data is:" ` `, end ` ` = ` ` "") ` ` print ` ` (statisti cs.pvariance (li)) `

Output:

` The variance of data is: 0.6666666666666667 The population variance of data is: 0.5555555555555556 `

3. stdev () : — This function returns the standard deviation (square root of sample variance) of the data. If the passed argument is empty, StatisticsError is thrown.

4. pstdev () : — This function returns the standard deviation of a population of (square root of the population variance) of the data. If the passed argument is empty, StatisticsError is raised.

 ` # Python code to demonstrate how it works ` ` # stdev () and pstdev () `   ` # import statistics for processing statistical operations ` ` import ` ` statistics `   ` # initializing list ` ` li ` ` = ` ` [` ` 1.5 ` ` , ` ` 2.5 ` `, ` ` 2.5 ` `, ` ` 3.5 ` `, ` ` 3.5 , 3.5 ] ````   # using stdev to calculate the standard deviation of the data print ( "The standard deviation of data is:" , end = "") print (statistics.stdev (li))   # using pstdev to calculate the standard deviation of population data print ( "The population standard deviation of data is:" , end = "") print (statistics.pstdev (li)) ```

Output:

` The standard deviation of data is: 0.816496580927726 The population standard deviation of data is: 0.7453559924999299 `

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