In statistics there are many useful indices that we can use to describe data. Some common terms are median, mode and mean.

Geometric mean indicates the central tendency of data by using the product of their values. It is used in data like interest rate, passing rate. The geometric mean is nth root of the product of n numbers. For example, the price of rice has increased by 3% and 5% over the past two years, then the geometric mean is √( 1.03 x 1.05 ) but not ( 1.03 + 1.05 ) ÷ 2.