Why CPI is more volatile than the GDPdeflator?

The Consumer Price Index (CPI) is generally more volatile than the GDP deflator because it captures changes in the prices of a fixed basket of goods and services consumed by households, which can fluctuate significantly due to seasonal factors, supply chain disruptions, and shifts in consumer preferences. In contrast, the GDP deflator reflects the prices of all domestically produced goods and services and adjusts for changes in the composition of output, making it less susceptible to short-term price changes. As a result, the CPI can show sharper movements in response to immediate economic conditions, while the GDP deflator provides a more stable long-term view of inflation.