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How food and fuel prices fluctuate

Detailed prices from the CPI


The consumer price index (CPI) follows the price of a basket of goods. The goods in the basket are determined by the purchases of an “average” U.S. household. Each item is tracked at multiple locations and for numerous varieties. The data are then aggregated to form the CPI.

The CPI has been a part of FRED for quite some time (since the early days if not the very beginning). FRED also offers some finer slices of consumer price data. The graph includes three examples: unleaded gasoline, peppers, and tomatoes. These are still aggregates, as the tracked prices come from many locations and, for tomatoes at least, across the various brands, varieties, and other ways of differentiating products.

What immediately gets our attention is how dynamic these lines are. The prices for these items change a lot and with little notice, which is why monetary policymakers in general prefer to look at price indices that exclude food and energy: Volatility can hide the bigger picture of inflation.

To reveal the extent of this volatility, we constructed the graph below, which compares the general CPI and the CPI without food and energy. For the latter, we even included the series without seasonal adjustment to demonstrate that seasonal adjustment does not remove the noise that policymakers are worried about.

How these graphs were created: For the first graph, start from the Average Price Data release table, check the items you want displayed, and click “Add to Graph.” For the second graph, start from the CPI graph and go to the “Edit Graph” panel. From there, open the “Add Line” tab and search for “CPI less food and energy”; add the monthly seasonally adjusted series. Repeat for the not seasonally adjusted series. Finally, adjust the units to “Percent Change from Year Ago” and click “Copy to All.”

Suggested by Christian Zimmermann.

View on FRED, series used in this post: APU0000712311, APU0000712406, APU000074714, CPIAUCSL, CPILFENS, CPILFESL


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