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A couple of days ago I was interested in how much cumulative inflation there was in the past three calendar years. I could have gone to a government site and calculated this statistic myself. However, having used ChatGPT several times in the past, I thought it could calculate this for me more quickly. So, I started a conversation with ChatGPT.
Me: How much did CPI increase from Jan 2022 to Jan 2025?
ChatGPT: The Consumer Price Index (CPI) increased by approximately 8.0% from January 2022 to January 2025. This reflects the overall rise in prices for goods and services over this period. Is there anything specific you’d like to know about the inflation or CPI?
This answer seemed understated to me, so I did some basic research. Since ChatGPT had footnoted the site “usinflationcalculator.com,” I decided to take a closer look at the data on that site. I was puzzled at what I saw versus what ChatGPT had told me, so I decided to query ChatGPT a bit more.
Me: If inflation was 6.5% in 2022, 3.4% in 2023, and 2.9% in 2024, why would the CPI only increase 8.0% during those three years?
ChatGPT: Great question! The CPI measures the overall change in prices for a basket of goods and services over time, while the inflation rate is the percentage change in price from one year to the next. To calculate the total increase over multiple years, we need to consider the compounding effect of inflation. Here’s a simplified example: