Introduction to Some Fundamental Statistical Concepts

A stack of spheres may be used as an example for the evaluation of data (Fig. 1), and in statistical terms the total number of individual spheres is then known as the population. One sphere extracted at random from the stack is referred to as a sample. In the example shown, each sphere is a natural sample unit, or individual. For instance, in order to determine the mean diameter of all the spheres, measurements are usually made on a random selection of the spheres, rather than every individual sphere, and the mean is then estimated from this sample of spheres, and the mean is then estimated from this sample of spheres (Fig. 1).