ABSTRACT
The standard deviation and variance are the simplest measure of dispersion around the central measures or tendency. It provides information regarding how the data items are distributed. The standard deviation is a measure of dispersion and it is the most frequently used statistical term. Although the practical applications of the standard deviation are limited to more sophisticated statistical methods, it is interesting that there is a relationship between the standard deviation and its more simple companion measure, the range. Deciles and percentiles are appropriate for larger populations that the people have been using in this chapter, but their interpretations are quite similar to the other equal-part measures. Using the mean and standard deviation, the people can decide the relative location of any data value. Two cost measures are frequently used in industry: cost factor and insurance-loss ratio. Much Until recently, most Environment, health and safety studies were retrospective comparisons.
