Abstract
The main part of the statistics is an investigating of the population by using samples. In this issue we state about a normal population first. In statistics we assume that a population follows a normal distribution in most cases. It is rational practically and theoretically. Another subject is the idea and methods of estimation (point estimation and interval estimation). We understand that point estimation itself is seldom used in the medical scene. However, the maximum likelihood estimation that is considered under the claims in point estimations is used as a value in several statistical methods. In interval estimations we can discuss the accuracy also.
