Commodity substitution bias

Commodity substitution bias is a problem with the calculation to find the change in an item's price change over time. It occurs when a new item which costs less is purchased instead of an item that was already available. This problem occurs because the CPI ( Consumer Price Index) is calculated from a "fixed basket" of goods and services.[1] The CPI ignores the substitution of the inexpensive item for the expensive item. So CPI says the price of the expensive item had increased.

References

  1. "A Better CPI". Federal Reserve Bank of San Francisco. Retrieved 2021-11-24.