List the four sources of bias in the CPI and briefly explain them

What will be an ideal response?

There are four potential biases. First is the new goods bias, which occurs when new, higher priced goods replace older goods. Second is the quality change bias, which occurs when the CPI fails to take account of quality improvements that raise prices. Third is the commodity substitution bias, which occurs when consumers shift their purchases away from goods whose relative prices rise toward lower priced goods. Last is the outlet substitution bias, which because with higher prices, people switch to low-cost discount stores.