# Statistics background¶

for understanding bandwidth scanners/generators

## Standard deviation¶

The formula for the sample standard deviation is

where are the observed values of the sample items, is the mean value of these observations, and N is the number of observations in the sample.

[stdev]

## Standard score¶

If the population mean and population standard deviation are known, the standard score of a raw score x[1] is calculated as

where:

μ is the mean of the population. σ is the standard deviation of the population.

[stdscore]