Estimating Population Dispersion From Very Small Samples Background Suppose a population has a mean m and a variance s 2 . For many types of population distributions at least two observations are required in order to estimate the population variance or standard deviation, but there are cases in which an estimate can be obtained from a single observation.
R are three important measures of sample variability.
In most of them we are interested in small sample sizes, where n is 1 or 2. Prove this equality. However, it is not generally true that S is an unbiased estimator of s . R , and use this result to find an unbiased estimator of s . A natural unbiased estimator of s is the sample mean.