The Standard Error is the
the standard
deviation of the mean of a
sample. If you:
 take a large number of samples, of
equal size, from a population
 calculate the mean of each sample
 calculate the standard deviation of
the sample means
you will have found the standard error.
The standard error is related to the population
(process) standard deviation by:
where 'n' is the sample size.
The standard error is less than the population
standard deviation because taking the mean
of a sample has an 'averaging' effect; the
larger and smaller values in the sample
tend to average out.
