What is Consumer Price Index?

It is designed to measure price changes in the expenditures of the consumer and is used as a measure of their cost of buying items.  So it measure the cost of  buying a fixed basket of goods and services representation of purchase of urban consumers.  Price related are calculated by this formula  Price rate   =  Current year  / base year x 100   items included in WPI are different from the items included in CPI.  The main drawback of consumer price index and it is related to or for urban consumer not for rural consumer