The importance of looking the average value is borne out by the fact that many individuals make use of the concept of variability in everyday decision-making, whether or not they compute a numerical measure Of the dispersion.
The degree to which numerical data tend to spread ut about the average value is called dispersion or variation of the data. Various measures of the dispersion (or variation) are available, the most common being the range, quartile deviation or semiinter quartile range, percentile, decile, and standard deviation. Range The range refers to the difference between the highest and the lowest score. It is the easiest and simplest to determine among the measures of variability because it depends only on the pair of extreme values. Example: Find the range of the frequency distribution below.