In previous lessons, properties of samples and of statistics computed on a random sample were discussed under a very general framework; in other words, under the idea that a random sample is selected from a population, but without specifying very much about that population. Now we consider the properties of a random sample and statistics based on a random sample that is selected from a population that is normally distributed.  When the population is normally distributed, a great many useful properties can be derived for common statistics. Additionally, many well-known sampling distributions are based on the normal distribution.