# Standard deviation
The standard deviation of the distribution is a characteristic of the dispersion of this distribution in the space of real numbers. The greater the standard deviation the larger the dispersion:

![Ecart type](baseUrl/statsDescriptives/ecart-type.png)


<center>Blue: Standard deviation = 1/Green: Standard deviation = 3</center>


The exact calculation of the distribution equation of the standard distribution is given by:

![equation](sigma^2=int(x^2*f(x)*dx))


Actually, like the average calculation, we rarely know the distribution of the equation but we do have a series of values. We therefore calculate an approximation of the standard deviation by calculating:

![equation](sigma^2=sum((x_i-mu)^2/(n-1)))

- n : total number of values


User Guide

Standard deviation