The coefficient of difference, also known as the coefficient of variation or dispersion, is the ratio of the standard deviation of a set of data to its average value. The greater the difference coefficient, the greater the imbalance between schools in the county; On the contrary, the smaller the difference coefficient, the smaller the degree of inter-school imbalance within the county. When considering the influence of school size on the degree of balance, the calculation formula is: cv=(s/x)* 100%.

, CV is the coefficient of difference, s is the standard deviation, and x is the county average.

Only one school doesn't count.