The index number is a statistical measure to express the relative changes that occur from time to time one or more characteristics or other variables that are expressed as a percentage.
In economics known there are 3 kinds of index numbers as follows.
1. Price index number
Price index number is a measure that shows the price change from a period to another.
2. Quantity index numbers
Quantity index numbers are index numbers that indicate the changes that occurred in the number of commodities that are consumed from time to time.
3. Value index numbers
The value index number is the index numbers that indicate changes in the value of money from one period to another. The value can be obtained by the multiplication between price and quantity.