By keeping the basket of goods and services the same when computing the CPI, the Bureau of Labor Statistics isolates the effects of price changes from the effect of any quantity changes that might be occurring at the same time.

Basket Of Goods

A fixed set of consumer products and services valued on a regular basis for measuring inflation in an economy or specific market.

Price Changes

Alterations in the cost of goods and services over time, which can be influenced by factors such as supply, demand, and inflation.

Quantity Changes

Variations in the amount of goods and services produced, purchased, or sold, often in response to market demand or supply conditions.