Consumer Price Index
A basket index rises from 120 to 123.6. Inflation over that period is (123.6/120 − 1) × 100 = 3%. If consensus for the same measure was 2.8%, the surprise is +0.2 percentage point, not a 0.2% relative index change.
Inflation readings and policy chronology
An inflation level, its publication and a central-bank decision are different events. Assess data available at the actual decision and market expectations, rather than connecting a later inflation peak with an earlier rate increase. A Poland-specific historical example is documented in Statistics Poland: February 2023 CPI and NBP: rates effective from 8 September 2022.
Index level and rate of change
An index records a level relative to a base, while month-on-month and year-on-year changes compare different periods. Lower positive inflation means slower price increases, not falling price levels. Base effects can materially change an annual reading.
Baskets and core measures
Population coverage, weights and exclusions depend on the agency. CPI, HICP and US PCE are different series. Check core definitions and seasonal adjustment in the methodology rather than assuming universal exclusions.
From a release to FX
Compare the matching series with forecasts, revisions and price components. A central bank may treat a one-off supply shock differently from persistent pressure. Higher inflation guarantees neither higher rates nor a stronger currency.
Primary source checked 11 October 2026: www.bls.gov.
FAQ
Does inflation falling from 5% to 3% mean cheaper shopping?
No. If both are positive annual inflation rates, the price level is still rising, just more slowly.
Can headline and core use the same consensus comparison?
No. A forecast must match the series, period, unit and seasonal-adjustment convention.
