Dispersion is a term used to describe the spread of something. In the case of dispersion21, it is a measure of how spread out the data points are in a data set. For example, if you had a group of numbers from 1 to 10, the dispersion21 would be the difference between the highest and lowest numbers (in this case, 10-1 = 9). Dispersion21 is a powerful measure of how much variation exists in the data set and it can be used to compare two sets of data to see which one is more spread out.