# Finding variance and standard deviation

Variance and standard deviation are very popular. They are a little bit more complicated to perform by hand, not that you would ever perform them by hand if you didn’t have to for the exam, but they are a much better measure of how dispersed your data is. Instead of giving you a rough idea based on the range, these tell you the average distance of every point from your mean.

## Variance

Variance is a measure of dispersion that looks at the squared deviation of a random variable from the mean of that variable. This equation looks a little scary, but we will break it down step by step:

=

It should be noted that this denominator (n-1) is used for samples. If you are using an entire population, then the denominator is just (). Let’s go over this briefly. is the sample variance, represents the value of each observation, represents the mean of the sample, and is the number of data points in your dataset. Let’s go ahead...