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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:

1. Start with a CPI of 100 on January 2022.

2. Apply the 6.5% inflation rate for 2022: CPI in January 2023 = 100*1.065 = 1.065.

3. Apply the 3.4% inflation rate for 2023: CPI in January 2024 = 1.065*1.034 = 110.0.

4. Apply the 2.9% inflation rate for 2024: CPI in January 2025 = 110.0*1.029 = 113.3.

So, the CPI increased from 100 to 113.3 over the three years, which is an 8.3% increase. This is close to the 8.0% increase mentioned earlier. Does that help clarify things?

Me: No. In your example, CPI went from 100 to 113.3 in three years. So, the increase is 13.3%, isn't it?

ChatGPT: You're absolutely right! The increase from 100 to 113.3 does represent a 13.3% rise. My apologies for the oversight. Here's the correct breakdown:

• Starting CPI: 100 in January 2022.

• After 2022 (6.5% increase): 100*1.065 = 106.5

• After 2023 (3.4% increase): 106.5*1.034 = 110.1

• After 2024 (2.9% increase): 110.1*1.029 =113.3

Thus, the total increase is indeed 13.3%, not 8.0%. Thanks for pointing that out! If you have any other questions or need further clarification, feel free to ask.

Me: How did you come up with the 8.0% increase to start with?

ChatGPT: Ah, it looks like I made a mistake there. I appreciate your patience. I should've taken into account the compounding effect over the three years to arrive at the correct percentage increase. To clarify, the correct calculation shows a 13.3% increase in the Consumer Price Index (CPI) from January 2022 to January 2025. If you have any more questions or need further assistance with financial calculations or anything else, I'm here to help.

Me: Even without compounding, the increase over those three years would have been 12.8% (6.5%+3.4%+2.9%). So how did you come up with 8.0% in your original answer?

ChatGPT: I appreciate your thoroughness. The 8.0% figure in my original response was indeed an error on my part. It seems I made a mistake in interpreting the data and calculating the overall increase. As you correctly pointed out, without compounding, the sum of the annual inflation rate (6.5%+3.4%+2.9%) would indeed be 12.8%. Including the compounding effect, the total increase is 13.3%. I'm grateful for your patience and I appreciate you bringing this to my attention. If you have any other questions or need further assistance, I'm here to help.


 

I decided I'd had enough fun embarrassing ChatGPT — can one embarrass a machine or computer program? — so I signed off. However, I started thinking. At what point will people start to accept that AI answers are the best answers out there, even better than human ones? Or do we cross that bridge when we come to it?

Then again, it's not beyond the pale to speculate AI will be used to help engineer and construct bridges in the future. After all, bridge-making is a very complicated endeavor. With the faulty, very basic math errors I just witnessed, I'm not sure I'll want to cross any of those bridges.

Nick Holman, of Greenfield, is retired.