A producer raises its selling price, but a shop keeps the shelf price unchanged. Neither figure is necessarily wrong. The US producer price index and consumer price index observe different transactions, which is why reading one as a preview of the other can lead a reader astray.
| What you need to know |
|---|
| CPI tracks prices paid by consumers; PPI tracks selling prices received by domestic producers. |
| The two indices cover different transactions and are not interchangeable. |
| A yearly change and a monthly change answer different questions. |
| An inflation release is evidence about prices, not an automatic interest-rate decision. |
Start with the transaction, not the acronym
The Bureau of Labor Statistics overview of PPI describes a family of indices measuring selling prices received by domestic producers. This includes services as well as goods. Calling PPI a measure of factory input costs misses both the selling-price distinction and the service industries it covers.
CPI looks from the purchaser’s side. The BLS consumer-price questions and answers explain its representative consumer basket. That is not a statement about what every household spent. Someone with an unusually high energy bill or a different housing arrangement can experience a change quite unlike the published average.
Taxes, distribution costs and subsidies can help explain differences between producer and consumer prices. Coverage also differs. A rise in PPI therefore does not establish that CPI must rise by the same amount, or in the following month. The starting supermarket example is hypothetical, not an observed price change.
Check what the percentage is comparing
Suppose an index rises from 100 to 104 over a year. Its annual change is 4 percent. Now suppose it rises from 104 to 104.2 in the next month. That monthly change is approximately 0.19 percent: divide 0.2 by 104, then multiply by 100. The increase of 0.2 index points is not exactly a 0.2 percent increase.
A falling annual rate can coexist with prices still rising month to month. Slower inflation does not, by itself, mean prices have returned to their earlier level. Check the comparison period and whether the series is seasonally adjusted before comparing two headlines.
For a euro-area comparison, the ECB’s explanation of inflation uses a weighted basket and the harmonised index of consumer prices. The weights reflect expenditure, rather than giving every product equal importance. Euro-area HICP and US CPI should not be treated as identical measures merely because both describe consumer inflation.
When the release arrives, the underlying table matters more than the headline alone. Check whether the quoted change is monthly or annual, whether it is seasonally adjusted, and whether it covers all items or excludes food and energy. Those choices describe different comparisons. An annual increase can remain elevated even when the latest month shows little movement; neither figure alone settles the next interest-rate decision.
