In statistics, the collection of n examples is called a sample of
size n. Strictly speaking, m is the sample mean
and v is the sample variance. The exact mean is the sample
mean for an infinitely large collection, and similarly for the variance.
We will be a little careless here and refer to the sample mean as the mean.
Also, it is more conventional to denote the mean by and the variance
by , where is called the standard deviation.
We use m, v ans s merely because Roman symbols are easier to enter in HTML.