There are several categories or types of potential bias in using changes in
the CPI as a measure of the change in the cost of living. 1) Substitution
bias occurs because a fixed market basket fails to reflect the fact that
consumers substitute relatively less for more expensive goods when relative
prices change. 2) Outlet substitution bias occurs when shifts to lower price
outlets are not properly handled. 3) Quality change bias occurs when
improvements in the quality of products, such as greate
