You can use one of the following three methods to calculate the standard deviation of a list in Python:

**Method 1: Use NumPy Library**

import numpy as np #calculate standard deviation of list np.std(my_list)

**Method 2: Use statistics Library**

import statistics as stat #calculate standard deviation of list stat.stdev(my_list)

**Method 3: Use Custom Formula**

#calculate standard deviation of list st.stdev(my_list)

The following examples show how to use each of these methods in practice.

**Method 1: Calculate Standard Deviation Using NumPy Library**

The following code shows how to calculate both the sample standard deviation and population standard deviation of a list using NumPy:

import numpy as np #define list my_list = [3, 5, 5, 6, 7, 8, 13, 14, 14, 17, 18] #calculate sample standard deviation of list np.std(my_list, ddof=1) 5.310367218940701 #calculate population standard deviation of list np.std(my_list) 5.063236478416116

Note that the population standard deviation will always be smaller than the sample standard deviation for a given dataset.

**Method 2: Calculate Standard Deviation Using statistics Library**

The following code shows how to calculate both the sample standard deviation and population standard deviation of a list using the Python statistics library:

import statistics as stat #define list my_list = [3, 5, 5, 6, 7, 8, 13, 14, 14, 17, 18] #calculate sample standard deviation of list stat.stdev(my_list) 5.310367218940701 #calculate population standard deviation of list stat.pstdev(my_list) 5.063236478416116

**Method 3: Calculate Standard Deviation Using Custom Formula**

The following code shows how to calculate both the sample standard deviation and population standard deviation of a list without importing any Python libraries:

#define list my_list = [3, 5, 5, 6, 7, 8, 13, 14, 14, 17, 18] #calculate sample standard deviation of list (sum((x-(sum(my_list) / len(my_list)))**2 for x in my_list) / (len(my_list)-1))**0.5 5.310367218940701 #calculate population standard deviation of list (sum((x-(sum(my_list) / len(my_list)))**2 for x in my_list) / len(my_list))**0.5 5.063236478416116

Notice that all three methods calculated the same values for the standard deviation of the list.

**Additional Resources**

How to Calculate the Standard Error of the Mean in Python

How to Calculate Mean Squared Error (MSE) in Python