The CPI assumes a fixed basket of goods over time. In fact, consumers are likely to change purchasing behavior over time by purchasing less of the goods whose prices have risen by relatively large amounts and by buying more of the goods whose prices have risen less or maybe even fallen. What problem does this cause for measuring the cost of living?

CPI

Consumer Price Index, a measure that examines the weighted average of prices of a basket of consumer goods and services, such as transportation, food, and medical care, often used as an indicator of inflation.

Cost of Living

The amount of money needed to sustain a certain level of living, including basic expenses such as housing, food, taxes, and healthcare.