[Mathematics | Probability | Statistics | Distribution] The variance of a set of numbers is the measure of how spread out they are. A variance of zero indicates that there is no variance which means all of the values are the same. Variance can never be represented with a negative number. The higher the variance the more spread out the values in the data set are.

Variance of a single trial, which includes a Bernoulli trial distribution, is the product of its success and failure rate. 

Variables:

`p` = Success Rate

Equation:

`p*(1-p)`

Notes

If set X is a discrete random variable,  the Bernoulli distribution of X with parameter p is defined such that

X has exactly two possible values:

    Pr(X=a)=p

    Pr(X=b)=1−p

where `0<= P <= 1`