What are the three effects that bias the measurement of cpi

Consumer price index (CPI) is weighted price index of basket of good that a consumer purchases each month. CPI is fixed in nature. It is an economic indicator. A rise in CPI indicates consumer inflation rate. The are type of bias that effects the measurement of CPI are: substitution bias, quality bias and outlet bias.

Explanation: Following are the bias:

Substitution Bias- it arises when prices in the consumer  basket increases and consequently low price alternatives or substitutes are opted by the consumer. As we know CPI is fixed-weight price index so the impact is not predicted accurately.Quality bias- It arises when any increase in technology increases the quality life of a product. Constant change in the quality of the product again does not reflect in consumer price index. Outlet bias- consumer shifts to new places or outlets as per their taste and preferences which is again not well represented by the CPI.