08-09-2014, 04:14 PM
They can be factors used to determine if there is a statistically important difference between mean values (the standard deviation is used in the computation of a confidence interval) such as Student's t test. Or if variances can be assumed or not assumed to be equal in doing Student's t test: you can evaluate this assumption by using the F test, where you compare variances of samples. So the values come in handy.
