Equilon FXKeep these questions in view.
- Exact CPI series and coverage
- Monthly or annual comparison
- Seasonally adjusted or unadjusted
- Category weights and the comparison with PCE
Use Full reading for the reasoning, worked example and original references.
What is being measured
The CPI measures changes in the prices consumers pay for a representative collection of goods and services. There are different population and geographical series, as well as headline and narrower aggregates. A precise reference names the index, not merely the word inflation.
Read the monthly and annual comparisons separately
A monthly change and a year-over-year change use different starting points. The annual comparison can move because of the latest observation and because of the observation leaving the window. Check seasonal adjustment before comparing monthly changes; do not silently mix adjusted and unadjusted series.
Look inside the aggregate
The contribution of a category depends on both its price change and its weight. A large move in a small category is not automatically the dominant explanation of the headline. The mix also matters for an interpretation of persistence: one broad number cannot describe every component’s behaviour.
Keep the policy link conditional
CPI can inform the inflation conversation, but the Fed’s longer-run objective is defined using PCE. The two indexes have different constructions. A CPI result is one input into a wider assessment of prices, activity and employment, not a mechanical instruction for the next policy decision.
The comparison window changes the story
A hypothetical index rises from 100 to 108 in year one and to 110.16 in year two. Annual inflation falls from 8% to 2%, while the price level increases again. A headline saying inflation fell is consistent with a household facing a higher level of prices.
What kind of statement is this?
Bureau of Labor Statistics / Monthly / Index and percentage changes
Identify the series and comparison before deciding what an inflation headline says.
This material does not establish a future policy decision, a live exchange rate or the direction of the next market move. Those questions require dated evidence and a specific comparison.
Annual inflation slows from 4% to 3%. Must the price level have fallen?
Keep the language clear Three useful definitions
CPI — Consumer Price Index. A family of consumer-price measures; identify the country, population, coverage and comparison period when reading a number. Read more ↗
Disinflation — A slowing rate of inflation. The price level can continue rising while the inflation rate falls. Read more ↗
Base effect — The influence of the earlier comparison value on a reported growth rate. An annual rate can change as an unusual earlier month moves out of the comparison. Read more ↗
Original references.
Institutional descriptions were prepared against these references for this edition. Follow the source for current decisions, releases and methodology. Numerical examples on this page are illustrative.