In plain terms — Inflation is a sustained change in the general price level. CPI, PCE and PPI cover different baskets, populations and production stages.
How to read consumer and producer price indexes, headline and core measures, weights, base effects and composition.
What it actually observes
CPI, PCE and PPI measure prices for different populations and stages of production. CPI follows a consumer basket, PCE uses more flexible weights and a different scope, while PPI records prices received by producers before many retail steps.
Headline and core inflation answer different questions. Excluding food and energy reduces volatility but does not create a pure signal or remove persistent shelter and service components.
Operational reading
Check the index level, monthly and annual rates, seasonal adjustment and component contributions. Base effects can lower the annual rate even while current prices continue to rise.
Compare a surprise with the exact consensus and its detail: goods, services, shelter and median measures can imply different paths. Pass-through from producer prices to margins or wages requires evidence, not a mechanical arrow from PPI to CPI.
Worked interpretation
Annual inflation can fall because a strong month leaves the comparison window; a recent annualised rate may show another impulse but is noisier.
Advanced level
Weights, substitution, quality adjustment and imputed prices shape every index. Trimmed-mean and median measures reduce extreme tails but answer a statistical question rather than defining future inflation.
Persistence work compares breadth, annualised speed and contracts with known lags. Survey and market expectations include different premia and must remain separate from realised prices.
Limits and common errors
One month, one volatile category or one core measure cannot describe the entire inflation process. Seasonal revisions, basket changes and fiscal or currency shocks limit mechanical comparisons across periods and countries.
Sources
- BLS, Consumer Price Index, official documentation — CPI data, relative-importance weights, methods and U.S. consumer-price releases.
- BEA, Personal Consumption Expenditures Price Index, official documentation — PCE inflation data linked to personal income, outlays and the national accounts.
- BLS, Producer Price Indexes, official documentation — methods and releases for changes in prices received by domestic producers.