Overview
The standard estimate of the sample mean is given by the population average.
{% \bar{x} = \frac{1}{n} \sum_{i=1}^n x_i %}
The estimate is unbiased.
Standard Error
The standard error is defined as
{% SE = \frac{\sigma}{\sqrt{n}} %}
where {% \sigma %} is standard deviation of the distribution and n is the sample size. The standard error gives
the standard deviation of the estimated value of the mean. Typically, the standard deviation of the sampling distribution
is unknown, in which case, the sample standard deviation is used instead, and the standard error becomes an approximation
of the standard deviation of the sample mean.