What does the consumer price index measure? B. the change in prices of specific goods and services over time. The consumer price index is also know as the CPI when reffering to this calculation. The CPI measures the weighted items of specific consumer goods and services by averaging them overtime. The CPI allows for comparison of the same products that consumers use on a daily basis and see how much they are using each year. This lets us know how the economy is doing as it relates to inflation. Inflation is the increase in prices and decline of the purchasing value of money in an economy.