Answer: Substitution bias:
Explanation:
Substitution bias explains a possible bias in economic index numbers if they do not incorporate data on consumer expenditures changing from products with a relatively high cost to a product with a cheaper price as the prices changes.
Substitution bias happens or can occurs when prices for products change relative to one another product. Consider how consumer expenditures are reflected in a consumer price index. Consumers will tend to buy more of the good whose price declined, and less of the now relatively more expensive good.
