Variance (S²_x , S²_y) is the square of the standard deviation.

 

Example: With it, we can determine some of the data dispersion measures.

Dispersion diagrams. Random and functional dependence: If the points of the cloud are placed according to the function chart, this function relates both variables and we will state that there is functional dependence.

If the points of the cloud are separated from the function chart, there is no function that relates both variables and we state that there is random dependence.