Pubblicato in: Banche Centrali, Stati Uniti

Usa. 2021Q2, PPI 6.2%, CPI 6.5%, PCE 4.2%. Spiegazione delle differenze.

Giuseppe Sandro Mela.

2021-09-05.

2021-08-28__ Usa Pec 001

Tutti gli indici di inflazione americani sono in costante crescita ed hanno già ampiamente superato i livelli di guardia.

Spetterà alla Harris-Biden Administration ed alla Fed l’arduo compito di decidere cosa fare.

Un errore potrebbe essere fatale per un Joe Biden già con alto tasso di esecrabilità ed una credibilità nulla.

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Non è facile districarsi nella selva delle sigle, ciascuna delle quali ha un suo preciso significato.

Ricordiamo soltanto come il PCE sia l’indice seguito dalla FED.

Lo US Bureau of Labor Statistics ha pubblicato un interessante Report

Differences between the Consumer Price Index and the Personal Consumption Expediture Prices Index.

In the United States, there are two primary measures of the prices paid by consumers for goods and services. One is the Consumer Price Index (CPI), which is produced by the Bureau of Labor Statistics (BLS); the other is the Personal Consumption Expenditures (PCE) price index, prepared by the Bureau of Economic Analysis (BEA). These two indexes are constructed differently and tend to behave differently over time. For example, in the fourth quarter of 2010, the CPI rose at a 2.6-percent annualized rate, while the PCE price index rose at a 1.7-percent annualized rate, a difference of 0.9 percentage point.1

               Categorizing the Differences

The differences between the CPI and PCE measures of inflation can be summarized into four categories or effects. The following sections quantify the magnitude of these effects over two distinct periods.

                         Formula effect.

The CPI and the PCE index are constructed from different index-number formulas. The CPI index is an average based on a Laspeyres formula, whereas the PCE index is based on a Fisher-Ideal formula. A Fisher-Ideal index is considered a “superlative” index in that it reflects consumer substitution

 among detailed items as relative prices change. In practice, superlative indexes are difficult to implement in real time because such indexes require expenditure data for the period that is current, and such data are not available. For example, data on household consumer expenditures that are used to estimate the CPI are not available for the current period. For the Consumer Price Index for Urban Consumers (CPI-U), a Laspeyres index provides an alternative to the Fisher- Ideal index.2

To estimate a “formula effect,” or the differences in the rates of growth between the CPI and PCE caused by the differences in formula, the detailed price and quantity data used to estimate the PCE index can be reaggregated with the use of a Laspeyres price-index formula.

                         Weight effect.

The relative weights assigned to each of the CPI and PCE categories of items are based on different data sources. The relative weights used in the CPI are based primarily on the Consumer Expenditure Survey, a household survey conducted for the BLS by the Census Bureau. The relative weights used in the PCE index are derived from business surveys—for example, the Census Bureau’s annual and monthly retail trade surveys, the Service Annual Survey, and the Quarterly Services Survey.

In order to estimate a “weight effect,” or the effect of using different weight sources on CPI and PCE index changes, CPI relative weights for comparable item categories can be used to estimate the PCE fixed-weight price index.

                         Scope effects.

The CPI measures the change in the out-of-pocket expenditures of all urban households and the PCE index measures the change in goods and services consumed by all households, and nonprofit institutions serving households. This conceptual difference means that some items and expenditures in the PCE index are outside the scope of the CPI. For example, the expenditure weights for medical care services in the CPI are derived only from out-of-pocket expenses paid for by consumers. By contrast, medical care services in the PCE index include those services purchased out of pocket by consumers and those services paid for on behalf of consumers—for example, medical care services paid for by employers through employer-provided health insurance, as well as medical care services paid for by governments through programs such as Medicare and Medicaid. These differences can also be isolated and measured, and can be referred to as “scope effects.”

                         Other effects.

A variety of remaining differences consisting of seasonal-adjustment differences, price differences, and residual differences must be taken into account for a complete understanding of the differences between the CPI and the PCE index. For example, the PCE index for airline fares is based on passenger revenues and the number of miles traveled by passengers. The CPI, however, is based on prices charged for air travel for sampled routes.

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