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General Methodology. (451 Kb. PDF File)
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Consumer Prices Index (CPI). Base 2001 (Summary)

The Consumer Price Index (CPI) is a statistical measurement of the evolution of the set of prices of goods and services that the resident population in family dwellings in Spain consumes.

In the Consumer Price Base 2001 Index the simple arithmetic average of the monthly indices of the said year calculated according to this system was made equal to 100.

The basic information on household expense on consumer goods and services was supplied by the Continuous Households Budgets Survey (CFBS). Eight quarters from the said survey were used (from the 2nd quarter of 1999 to the 1^st quarter of 2001). These weightings will be updated annually by incorporating new information from the CFBS. In this way the CPI will reflect changes in consumer habits which have occurred in the twelve months subsequent to the last update.

The reference band or population group whose expenses structure serves as a basis for the selection of the representative articles and the calculation of the weightings of the same is the population resident in family dwellings in Spain.

The consumption field is made up of all expenses that population households dedicate to consumption; therefore, investment that these households make are excluded. Only real costs that the population makes are taken into account which implies the exclusion of any imputed cost operation, such as those relative to auto consumption, auto supply, imputed rent, wages in kind or subsidised consumption such as health or education.

From more than 500 expense entries from the CFBS 484 articles have been selected, classified into 12 groups whose prices evolution represents total consumer goods and services. The set of these articles is commonly known as shopping basket.

To calculate the index corresponding to period t a Laspeyres index that consists of referring of the price of the current period to the prices for december of the year immediately before and facilitates the updating the weightings not causing a rupture in the CPI series is used.

The formulation is the following:

The weighting of an article represents the proportion of expense made on this article with respect to total expenditure made by households. The weightings structure will be revised annually for certain levels of geographical and functional breakdown; in this revision apart from studying the convenience or not of broadening the composition of the coverage of products as well as the possibility of modifying some of the treatments used in the calculation of the index.

The index is elaborated with approximately 200.000 prices of which around 30.000 establishments distributed in 141 municipalities have provided information.

Indices are calculated for Spain, the seventeen Autonomous Communities, the fifty provinces, Ceuta, Melilla and the set made up of these two cities.

Weightings