Consumer Price Index (CPI)

• 1. Contact

  • 1.1. Contact organisation

    • National Statistics Institute of Spain

  • 1.5. Contact mail address

    • Avenida de Manoteras 50-52 - 28050 Madrid

• 2. Metadata update

  • 2.1. Metadata last certified

    • 14/01/2026

  • 2.2. Metadata last posted

    • 14/02/2025

  • 2.3. Metadata last update

    • 14/01/2026

• 3. Statistical presentation

  • 3.1. Data description

    • The purpose of the Consumer Price Index (CPI) is to measure the evolution of the prices of consumer goods and services acquired by the households resident in Spain.

      The CPI consumption field does not include goods received in kind, as self-consumption, self-supply, salary in kind, free or bonus meals and rent imputed to the dwelling in which the households reside, when they are owners.

      The precision with which this short-term indicator measures the evolution of prices depends on two features that every CPI must have: time representation and comparability.

      The degree of representation of the CPI is determined by the adaptation of this indicator to the economic reality of the moment. In order to achieve this, the selected items that are part of the basket of goods and services must be the most frequently consumed by most of the population, the establishments of the sample must be the most visited, and the relative importance of each item in the basket of goods and services responds to household consumption trends.

      On the other hand, the CPI is designed for drawing comparisons in time. Time comparability demands that all elements that define this indicator remain steady throughout time except the prices collected monthly. This way, it is achieved that any variation in the CPI is only due to changes in the prices of selected items and not due to changes in the methodological content of the indicator.

  • 3.2. Classification system
    • • Comunidades y Ciudades Autónomas

        • 01   Andalucía 02   Aragón 03   Asturias, Principado de 04   Balears, Illes 05   Canarias 06   Cantabria 07   Castilla y León 08   Castilla - La Mancha 09   Cataluña 10   Comunitat Valenciana 11   Extremadura 12   Galicia 13   Madrid, Comunidad de 14   Murcia, Región de 15   Navarra, Comunidad Foral de 16   País Vasco 17   Rioja, La 18   Ceuta 19   Melilla

      • ECOICOP
        • Clasificación Europea de Consumo Individual por Objetivo Ver clasificación
      • Grupos especiales

        • 01   Alimentos con elaboración, bebidas y tabaco 02   Alimentos sin elaboración 03   Bienes industriales 04   Servicios sin alquiler de vivienda 05   Carburantes y combustibles 06   Bienes industriales duraderos 07   Productos energéticos 08   General sin alimentos, bebidas y tabaco 09   General sin alquiler de vivienda 10   General sin carburantes ni combustibles 11   General sin productos energéticos 12   General sin alimentos no elaborados ni productos energéticos 13   General sin servicios (incluye alquiler de vivienda) 14   General sin servicios ni alquiler de vivienda 15   General sin alimentos ni bebidas ni tabaco ni alquiler de vivienda 16   General sin alimentos ni bebidas ni tabaco ni carburantes ni combustibles 17   General sin alimentos ni bebidas ni tabaco ni productos energéticos 18   General sin alimentos ni bebidas ni tabaco ni servicios (incluido alquiler de vivienda) 19   General sin alimentos ni bebidas ni tabaco ni servicios ni alquiler de vivienda 20   Bienes industriales no duraderos 21   General sin tabaco 22   Alimentos y bebidas 23   Alimentos elaborados 24   Bienes industriales sin energía 25   Servicios 26   Alimentos, bebidas y tabaco 27   Alimentos no elaborados y productos energéticos 28   Bienes industriales sin productos energéticos 29   General sin carburantes ni combustibles líquidos

      • Provincias

        • 02   Albacete 03   Alicante/Alacant 04   Almería 01   Araba/Álava 33   Asturias 05   Ávila 06   Badajoz 07   Balears, Illes 08   Barcelona 48   Bizkaia 09   Burgos 10   Cáceres 11   Cádiz 39   Cantabria 12   Castellón/Castelló 13   Ciudad Real 14   Córdoba 15   Coruña, A 16   Cuenca 20   Gipuzkoa 17   Girona 18   Granada 19   Guadalajara 21   Huelva 22   Huesca 23   Jaén 24   León 25   Lleida 27   Lugo 28   Madrid 29   Málaga 30   Murcia 31   Navarra 32   Ourense 34   Palencia 35   Palmas, Las 36   Pontevedra 26   Rioja, La 37   Salamanca 38   Santa Cruz de Tenerife 40   Segovia 41   Sevilla 42   Soria 43   Tarragona 44   Teruel 45   Toledo 46   Valencia/València 47   Valladolid 49   Zamora 50   Zaragoza 51   Ceuta 52   Melilla

      • Rubricas IPC 1

        • 01   Cereales y derivados 02   Pan 03   Carne de vacuno 04   Carne de ovino 05   Carne de porcino 06   Carne de ave 07   Otras carnes 08   Pescado fresco y congelado 09   Crustáceos, moluscos y preparados de pescado 10   Huevos 11   Leche 12   Productos lácteos 13   Aceites y grasas 14   Frutas frescas 15   Frutas en conserva y frutos secos 16   Legumbres y hortalizas frescas 17   Preparados de legumbres y hortalizas 18   Patatas y sus preparados 19   Café, cacao e infusiones 20   Azúcar 21   Otros preparados alimenticios 22   Agua mineral, refrescos y zumos 23   Bebidas alcohólicas 24   Tabaco 25   Prendas de vestir de hombre 26   Prendas de vestir de mujer 27   Prendas de vestir de niño y bebé 28   Complementos y reparaciones de prendas de vestir 29   Calzado de hombre 30   Calzado de mujer 31   Calzado de niño 33   Vivienda en alquiler 34   Calefacción, alumbrado y distribución de agua 35   Conservación de la vivienda 36   Muebles y revestimientos de suelo 37   Textiles y accesorios para el hogar 38   Electrodomesticos y reparaciones 39   Utensilios y herramientas para el hogar 40   Artículos no duraderos para el hogar 41   Servicios para el hogar 42   Servicios médicos y similares 43   Medicamentos y material terapéutico 44   Transporte personal 45   Transporte público urbano 46   Transporte público interurbano 47   Comunicaciones 48   Objetos recreativos 49   Publicaciones 50   Esparcimiento 51   Educación infantil y primaria 52   Educación secundaria 53   Educación universitaria 54   Otros gastos de enseñanza 55   Artículos de uso personal 56   Turismo y hostelería 57   Otros bienes y servicios

  • 3.3. Sector coverage

    • The CPI covers all households in Spain, specifically the goods and services acquired by those households.

  • 3.4. Statistical concepts and definitions
    • • Adjustment due to change in quality

        • Estimate of the part of the price difference between the new item (substitute) and the old one (substituted) due to the difference in quality between the two.

      • Aggregate index

        • Weighted arithmetic average of basic indices.

      • Basic Index

        • Quotient between the average price for the current month and the average price for December of the previous year (multiplied by 100). The indices have no measurement unit and show price variation from the base period until the current month.

      • Basket

        • Set of products for which the price is collected monthly.

      • Change in quality

        • A change that occurs when a subvariety of the basket is substituted by another with different features, that imply a change in usefulness of the product.

      • Contribution

        • The contribution of a product measures how much the general index would change if only the price of the aforementioned product changed (in other words, if the other prices remain constant).

      • HICP Prices

        • The prices considered for calculating the HICP are effective prices for selling to the public, with cash payment, including taxes and net of subsidies.

      • Product or aggregate weight

        • The weight of a product or aggregate is the relative importance it has in relation to the rest of products or aggregates in the basket, according to expenditure/income.

      • Scanner data

        • Detailed data on sales of consumer goods obtained by scanning the bar codes for individual products at electronic points of sale in retail outlets. The data can provide detailed information about quantities, characteristics and values of goods sold, as well as their prices. Scanner data constitute a source of data with considerable potential for CPI purposes and, for this reason, a lot of countries are including them in the CPI compilation.

      • Specification

        • Set of features that define, identify and determine each specific item.

      • Variation

        • This shows the evolution of prices between the time periods.

  • 3.5. Statistical unit

    • Households resident in family dwellings in Spain.

  • 3.6. Statistical population

    • All households resident in family dwellings in Spain, whether urban or rural and regardless of their income.

      This excludes the expenses of persons resident in collective households or institutions (convents, nursing homes, prisons, etc.) and the expenses of non-residents.

  • 3.7. Reference area

    • The geographical scope constitutes all the national territory.

      Brokendown information is calculated for the 52 provinces.

  • 3.8. Time coverage

    • The survey is carried out monthly.

      Results are available from January 1961.

      The Base 2021 index series start January 2002. The Base 1992 index series cover from January 1961 to December 2001.

  • 3.9. Base period

    • Base Period

      The base period or reference period of the index is the year 2021 (2021=100).

      Reference period for the prices

      It is the period in which its prices are compared to current prices, that is, the period chosen for the calculation of the elementary indices.

      With the calculation formula used for the CPI, Base 2021 – chain-linked Laspeyres – the reference period for the prices varies each year and it is the month of December of the year immediately before the one considered.

      Reference period for the weights

      It is the reference period of the data from which the weightings that serve as the CPI structure are obtained.

      From january 2023, for the year t, the calculation of CPI, base 2021, weights has been carried out using the data from the National Accounts corresponding to the year (t-2). Subsequently, these weights were updated with information on prices and quantities so as to reference them with date December (t-1).

      Weights are updated annually.

• 4. Unit of measure

  • 4.1. Unit of measure

    • - Indices

      Indices are compiled as ratios of prices in a given month to prices in the reference month (December of the previous year) multiplied by 100. Therefore indices are unitless.

      - Rates of change

      All rates of change are usually given as percentage changes.

      - Weights

      For each item or group of items, weights represent the corresponding percentage share of the total expenditure.

• 5. Reference period

  • 5.1. Reference period

    • The data reference period is the month.

      Data referred to the period: Mensual A: 2025 MES: 12

• 6. Institutional mandate

  • 6.1. Legal acts and other agreements

    • The compilation and dissemination of the data are governed by the Statistical Law No. 12/1989 "Public Statistical Function" of May 9, 1989, and Law No. 4/1990 of June 29 on “National Budget of State for the year 1990" amended by Law No. 13/1996 "Fiscal, administrative and social measures" of December 30, 1996, makes compulsory all statistics included in the National Statistics Plan. The National Statistical Plan 2009-2012 was approved by the Royal Decree 1663/2008. It contains the statistics that must be developed in the four year period by the State General Administration's services or any other entity dependent on it. All statistics included in the National Statistics Plan are statistics for state purposes and are obligatory. The National Statistics Plan 2025-2028, approved by Royal Decree 1225/2024, of  3 December, is the Plan currently implemented. This statistical operation has governmental purposes, and it is included in the National Statistics Plan 2025-2028. (Statistics of the State Administration).

      Order EHA/3411/2011, of 5 December 2011, sets out the new Consumer Price Index system, Base 2011.

  • 6.2. Data sharing

    • The exchanges of information needed to elaborate statistics between the INE and the rest of the State statistical offices (Ministerial Departments, independent bodies and administrative bodies depending on the State General Administration), or between these offices and the Autonomic statistical offices, are regulated in the LFEP (Law of the Public Statistic Function). This law also regulates the mechanisms of statistical coordination, and concludes cooperation agreements between the different offices when necessary.

• 7. Confidentiality

  • 7.1. Confidentiality - policy

    • The Statistical Law No. 12/1989 specifies that the INE cannot publish, or make otherwise available, individual data or statistics that would enable the identification of data for any individual person or entity. Regulation (EC) No 223/2009 on European statistics stipulates the need to establish common principles and guidelines ensuring the confidentiality of data used for the production of European statistics and the access to those confidential data with due account for technical developments and the requirements of users in a democratic society

  • 7.2. Confidentiality - data treatment

    • INE provides information on the protection of confidentiality at all stages of the statistical process: INE questionnaires for the operations in the national statistical plan include a legal clause protecting data under statistical confidentiality. Notices prior to data collection announcing a statistical operation notify respondents that data are subject to statistical confidentiality at all stages. For data processing, INE employees have available the INE data protection handbook, which specifies the steps that should be taken at each stage of processing to ensure reporting units' individual data are protected. The microdata files provided to users are anonymised.

      In the case of the CPI, only aggregate information that does not allow obtaining information on microdata is published.

• 8. Release policy

  • 8.1. Release calendar

    • The advance release calendar that shows the precise release dates for the coming year is disseminated in the last quarter of each year.

  • 8.2. Release calendar access

    • The calendar is disseminated on the INEs Internet website (Publications Calendar)

  • 8.3. User access

    • The data are released simultaneously according to the advance release calendar to all interested parties by issuing the press release. At the same time, the data are posted on the INE's Internet website (www.ine.es/en) almost immediately after the press release is issued. Also some predefined tailor-made requests are sent to registered users. Some users could receive partial information under embargo as it is publicly described in the European Statistics Code of Practice

• 9. Frequency of dissemination

  • 9.1. Frequency of dissemination

    • The CPI is disseminated monthly.

• 10. Accessibility and clarity

  • 10.1. News release

    • The results of the statistical operations are normally disseminated by using press releases that can be accessed via both the corresponding menu and the Press Releases Section in the web

  • 10.2. Publications

    • Press releases, on the day of publication.

      Generic publications such as Spain in Figures, the Statistical Yearbook of Spain and the Monthly Statistical Bulletin contain information regarding the CPI.

  • 10.3. On-line database

    • INEbase is the system the INE uses to store statistical information on the Internet. It contains all the information the INE produces in electronic formats. The primary organisation of the information follows the theme-based classification of the Inventory of Statistical Operations of the State General Administration . The basic unit of INEbase is the statistical operation, defined as the set of activities that lead to obtaining statistical results on a determined sector or subject based on the individually collected data. Also included in the scope of this definition are synthesis preparation.

      The online database of the CPI, which contains information on indices, variations and weightings may be accessed in the following link:

      https://www.ine.es/dyngs/INEbase/en/operacion.htm?c=Estadistica_C&cid=1254736176802&menu=ultiDatos&idp=1254735976607

      Number of entries in 2024 was 

      - Number of entries to data bases AC1=3,526,823 - Number of entries to metadata bases AC2=5,949

  • 10.4. Micro-data access
    • A lot of statistical operations disseminate public domain anonymized files, available free of charge for downloading in the INE website Microdata Section

      No information on microdata is provided for the CPI.

  • 10.5. Other

    • All information that may be provided on the CPI is available on the INE website.

  • 10.6. Documentation on methodology

    • - Base 2021:

      Metodología: https://ine.es/metodologia/t25/principales_caracteristicas_base_2021.pdf

      - Base 2016:

      Methodology: https://www.ine.es/en/metodologia/t25/t2530138_16_en.pdf

      Press release regarding the base change: https://www.ine.es/en/prensa/ipc_base_2016_en.pdf​

      - Base 2011:

      Methodology: https://www.ine.es/en/metodologia/t25/t2530138_en.pdf

      Press release regarding the base change: https://www.ine.es/en/prensa/np701_en.pdf

      - Base 2006:

      Methodology: https://www.ine.es/en/daco/daco43/metoipc06_en.pdf

      Press release regarding the base change: https://www.ine.es/en/prensa/np446_en.pdf

      - Base 2001:

      Methodology: https://www.ine.es/en/ipc01/metodologia_ipc2001_en.pdf

      Most important characteristics of the new system: https://www.ine.es/en/ipc01/index_en.html

      The filled out metadata rate is: AC3=100%

  • 10.7. Quality documentation

    • The sections 10.6 to 17 of this document are the User-oriented Quality report for this statistics.

      On the other hand, there are no documents on sampling errors, because the CPI is a statistics with non-probabilistic sampling.

• 11. Quality management

  • 11.1. Quality assurance

    • Quality assurance framework for the INE statistics is based on the ESSCoP, the European Statistics Code of Practice made by EUROSTAT. The ESSCoP is made up of 16 principles, gathered in three areas: Institutional Environment, Processes and Products. Each principle is associated with some indicators which make possible to measure it. In order to evaluate quality, EUROSTAT provides different tools: the indicators mentioned above, Self-assessment based on the DESAP model, peer review, user satisfaction surveys and other proceedings for evaluation.

      The Spanish CPI is a high-quality statistical operation. Its methodology follows the recommendations of the "Consumer Price Index Manual. Theory and Practice (2020)" published by the International Labour Organization (ILO), which is internationally agreed.

      Sample size is broad enough (around 220,000 prices) so as to allow publishing highly-accurate results at provincial level.

      It is designed to ensure a continuous assessment of data quality. The collected prices are first validated in the moment they are recorded and all price changes must be justified in order to ensure data quality. Subsequently, the prices are edited and validated again from the Central Services.

  • 11.2. Quality assessment

    • The CPI is an up to day indicator since it revises its methodological system permanently in order to improve it. Besides, it is dynamic, because annually it reviews the weights for certain levels of functional disaggregation and includes in the shortest time any change detected in the market: the appearance of new products, changes in the consumption structure or in the sample of municipalities or outlets. In addition, it establishes the base changes every five years, carrying out a complete review of the methodology and the sample and the updating of weights at all levels of disaggregation.

      Therefore, and thanks to the calculation methodology applied, it is an indicator with a high representativeness.

      However, there are some aspects where the CPI needs to be improved to increase the process efficiency and the indicator accuracy. These aspects are related mainly to the methods used for collecting prices, since the consumers have changed the ways to access to the market and they are now much more diverse, and the new technologies also allow methods of obtaining the information faster and more efficiently.

      In that sense, form Janury 2020, the CPI includes "scanner data" in its compliation. This method is based on the use of the information registered by the companies in the cash line of their establishments. The fundamental aspects of this new method for price collection are its methodological treatment, from its obtaining until its use, and the conceptual change that it supposes with respect to the traditional collection, when substituting prices of acquisition by unit values.

      Besides, we are currently working on projects that will improve representativeness, quality and precision. These are the following:

      - Extension of the use of scanner data, based on the use of the information registered by the companies in the cash line of their establishments. The fundamental aspects for its implementation are its methodological treatment, from its obtaining until its use, and the conceptual change that it supposes with respect to the traditional collection, when substituting prices of acquisition by unit values.

      - Use of web scraping, that is, massive collection of internet data. Conceptually it is very similar to the traditional methodology, regarding the use of offer prices, but it is necessary to develop a specific computer software.

• 12. Relevance

  • 12.1. User needs

    • The main CPI users are:

      - The Bank of Spain.

      - The Ministry of Economy and Competitiveness.

      - Other public administrations (rest of ministries, Autonomous Communities, town councils, etc.).

      - Companies and financial institutions.

      - Economic analysts and universities.

      - Individuals.

      The CPI is important and greatly used in economic, legal and social scopes. One of its most important uses is as a measure of inflation. It is also used for the revision of property leasing contracts, as a reference in wage bargaining, for fixing pensions, updating insurance premiums and other types of contracts and as a deflator in Spanish National Accounts.

      In order to satisfy user needs, data is published with the greatest possible disaggregation.

  • 12.2. User satisfaction

    • The INE has carried out general user satisfaction surveys in 2007, 2010, 2013,  2016 and 2019 and it plans to continue doing so every three years. The purpose of these surveys is to find out what users think about the quality of the information of the INE statistics and the extent to which their needs of information are covered. In addition, additional surveys are carried out in order to acknowledge better other fields such as dissemination of the information, quality of some publications...

      On the INE website, in its section Methods and Projects / Quality and Code of Practice / INE quality management / User surveys are available surveys conducted to date.(Click  next link)

       

      The CPI is one of the surveys that is best valued by users in terms of satisfaction.

  • 12.3. Completeness

    • Indices for all levels of ECOICOP from 2 to 5 digits are compiled.

      There is no specific regulation regarding the breakdown level to which the CPI shall be calculated.

      The rate of compulsory available results for the CPI, base 2021, is R1=100%.

• 13. Accuracy and reliability

  • 13.1. Overall accuracy

    • The procedure for price collection, establishment selection (the most representative of the municipality) and the basket of goods and services (the most consumed items) allows obtaining a high level of accuracy and reliability of these statistics.

  • 13.2. Sampling error

    • Sampling errors are not calculated for CPI because the CPI sample is based on non-probabilistic methods.

      In order to minimise possible errors, a price sample that is as large as possible is used.

  • 13.3. Non-sampling error

    • During the entire statistical process, non-sampling errors are monitored.

      There is no unit non-response rate in the CPI since the prices are collected visiting outlets by INE personnel.

      Nevertheless, when a price is occasionally missing (the product is not available in the outlet during collection) an item non-response rate exists. In such cases estimation procedures are carried out, applying  the same variation as the rest of the same product's prices to the previous period's price.

      In year 2025 the average item non-response rate is A5 = 4.08%.

      Moreover, applications have been developed so as to detect and reduce the possible errors during price collection and recording.

      In year 2025, the average imputation rate is A7 = 1.71%.

• 14. Timeliness and punctuality

  • 14.1. Timeliness

    • The CPI flash estimator is published on the next to last day of the reference month and it provides estimated information on the annual rate of this indicator, therefore, TP1=−2 days

      CPI results at all breakdown levels are published near day 13 of the month following the reference month, therefore, TP2=13 days

  • 14.2. Punctuality

    • Survey results are published according to the Short-term Statistics availability calendar of the INE ( https://www.ine.es/en/daco/daco41/calen_en.htm).

      All CPI publications have been published on the date included in the availability calendar, therefore, TP3=100%.

• 15. Coherence and Comparability

  • 15.1. Comparability - geographical

    • CPI data is totally comparable among regions, since the calculation method of this statistical operation in all of its stages is the same for all the national territory.

      Furthermore, in order to compare inflation among European Union Countries, the data provided by the Harmonised Indices of Consumer Prices (HICP) shall be used, which is compiled for this purpose.

  • 15.2. Comparability - over time

    • The index series have a break in 2001 due to the introduction of discounted prices. Therefore, there are two CPI series: from January 1961 to 2001, Base 1992, and from January 2002 to present, Base 2021.

      In spite of the index series break, the objective of the CPI continues to be fulfilled, since it is possible to calculate variations for any period of time, since January 1961 to present.

      Therefore, up to December 2025, the length of the series of comparable data is CC2=780 months.

  • 15.3. Coherence - cross domain

    • The CPI is coherent with the Harmonised Indices of Consumer Prices (HICP), also compiled by INE.

      Nevertheless, these two indicators are conceived with different purposes and are not regulated by the same regulation, therefore there are some differences in their methodologies and coverage:

      Consumption expenditure of residents in group households or institutions (convents, nursing homes, prisons, etc.) as well as expenditure within the economic territory by non-residents are included in the HICP but not in the national CPI.

      Consumption expenditure of residents outside of the national territory is included in the CPI but not in the HICP.

      During out-of-season months, prices for seasonal clothing and footwear products are estimated for the HICP, but not for the CPI.

  • 15.4. Coherence - internal

    • CPIs are internally coherent. Aggregations are carried out from the lowest geographical and functional information levels to the highest.

• 16. Cost and burden

  • 16.1. Cost and burden

    • In the 2025 Annual Program, the estimate of the necessary budget appropriation to finance these statistics is 7,840.84 thousand euro.

      There is no burden on respondents, since collection is carried out by INE interviewers.

• 17. Data revision

  • 17.1. Data revision - policy

    • The INE of Spain has a policy which regulates the basic aspects of statistical data revision, seeking to ensure process transparency and product quality. This policy is laid out in the document approved by the INE board of directors on 13 March of 2015, which is available on the INE website, in the section "Methods and projects/Quality and Code of Practice/INE’s Quality management/INE’s Revision policy" (link).

      This general policy sets the criteria that the different type of revisions should follow:  routine revision- it is the case of statistics whose production process includes regular revisions-; more extensive revision- when methodological or basic reference source changes take place-; and exceptional revision- for instance, when an error appears in a published statistic-.

  • 17.2. Data revision - practice

    • CPI data is final the moment it is published for the first time and is therefore not subject to revision.

• 18. Statistical processing

  • 18.1. Source data

    • The data used for the compilation of the CPI is obtained from the direct collection of prices in the outlets and from scanner data.

      Sample size consists in 462 consumption goods and services whose prices are collected directly from outlets, for which around 220,000 prices are collected in approximately 33,000 outlets all over Spain, and 737 consumption goods, whose prices are obtained by scanner data.

  • 18.2. Frequency of data collection

    • Prices are collected once a month, from the 1st to the 22nd day of the reference month, for most items.

      Prices for fresh products (fruit, vegetables, fresh meat and fish, eggs and potatoes) are collected 3 times a month in capital municipalities and twice a month in non-capital municipalities.

      Moreover, the prices of some items are collected during the entire month, such as: petrol, tobacco, airline tickets, etc.

      The prices obtained by scanner data include data of the 3 "central" weeks in the month.

  • 18.3. Data collection

    • Price collection for the CPI is mainly carried out by means of a digital questionnaire. Starting January 2020, scanner data is implemented for some items, is that to say, detailed data on sales of consumer goods obtanied by 'scanning' the bar codes for individual products in all chain's outlets. These database are provided directly by companies to INE.

      Some items are collected by other means (Internet, telephone calls, etc.)

      Since collection is carried out by INE interviewers, non-response does not exist.

      The questionnaire includes the items for which the price will be collected in each establishment, with a detailed description of its characteristics (specifications), which allows the interviewer to identify the exact product. It also includes information on the price of the previous month.

  • 18.4. Data validation

    • Questionnaire recording and filtering is carried out in the provincial delegations, this way establishing the necessary control regulations so as to guarantee an appropriate quality level during the entire process. This allows monitoring, already in this stage, recording errors (the recording application detects variations above or below a threshold).

      After the data is collected and recorded, it is firstly filtered in the delegations. In the delegation, the prices that have variations above or below a specific threshold shall be validated.

      Moreover, repeated interview processes are carried out so as to ensure the quality and reliability of the collected information.

  • 18.5. Data compilation

    • - Edition and validation

      The prices sent from the provincial delegations are filtered in the Central Services and all variations above or below specific thresholds are confirmed.

      - Centralised items

      There are some items whose prices are monitored from the INE Central Services. These types of items are goods and services that have one or several of the following characteristics:

      - their prices are the same in a wide geographical area,

      - their prices are subject to fees published in the Official State Gazette,

      - there are few companies that sell the item,

      -a perfectly defined directory of informants is available,

      - items that regularly change quality (such as technology items), which makes it difficult to carry out quality adjustments; since they are collected in a centralised way, the treatment of these adjustments is standardised.

      These items are known as centralised collection items.

      - Calculation of indices

      First the elementary indices are calculated as the quotient of the geometric average of the prices collected during the month over the prices collected in December of the previous year.

      Subsequently, the elementary indices are aggregated using a weighted arithmetic average.

      - Weights

      The main weighting sources of the CPI are the Spanish National Accounts and the Household Budget Survey.

      The expenditure used to compilate the weights is the household final monetary consumption expenditure, according the definition of the European System of Accounts (ESA).

      Moreover, for the most brokendown information, other sources such as the offer is used.

      There are weights for each item in all provinces.

      - Treatment of seasonal items

      In the Spanish CPI, fresh fruit and fresh vegetables are regarded as seasonal products, because they are not available for purchase all year.

      The calculation method used to measure price variations of these products consists in using a monthly basket with the fresh fruit andfresh vegetables that are in season each month.

      The calculation method for fresh fruit andfresh vegetables that are available in the market all year, is the same for any other product in the basket.

      - Treatment of offers and sales

      The discounts are taken into account in the CPI, prices with occasional offers as well as seasonal sales are collected.

      - Treatment of missing price

      When an item is occasionally not available for sale in the moment of collection, its price is estimated using the variations of the rest of item prices collected in the province.

      - Treatment of missing items and replacements

      When the price of an item has been missing twice or the item ceases to be on the market, the item shall be replaced as soon as possible. The new product will be selected in the same establishment and with the same quality, except if changes in the market suggest selecting a product with a different quality.

      The first selection of products and establishments is carried out in such a way that the most sold products and the establishments with the greatest number of visitors are represented in the sample. This representation shall me maintained when carrying out replacements.

      - Adjustments due to quality change in the CPI

      When one product is replaced by another, an adjustment shall be carried out so as to determine what part of the price difference between both items is due to different quality between them.

      Generally, the replacement product shall have a similar quality to the one replaced, but when for some reason the quality between both is different (different variety, different brand, etc.), an adjustment quotient is calculated so as to guarantee variations in the index caused exclusively by price variations.

      There are different quality adjustment methods according to the type of product and the available information. Some of these methods are:

      - Same quality adjustment: the quality of both products is the same, therefore their prices are directly compared. This procedure is usually applied to clothing and footwear.

      - Information provided by experts: product experts or specialists are asked what part of the price difference between items (replacement and replaced) is due to the difference of quality between both. It is used in cars, telephone services and other.

      - Overlap prices: the value of the quality difference between the replaced item and the replacement item is the difference between them in the overlap period, that is, during the period in which both items are for sale. It is applied when the information on the prices of both items during the overlap period is available.

      - Imputation prices: imputation of the average price variation of an aggregate to which the item belongs. It is used when there is no information available that allows carrying out another type of adjustment.

      - Hedonic regression methods this method is part of the hypothesis that the price of an item may be expressed regarding a set of characteristics by means of a regression model ( linear or non-linear). It is used with washing machines and televisions.

      - Capacity change: it is used to compare the price between two products that have the exact same characteristics except the quantity, comparing the price of both products for the same size.

  • 18.6. Adjustment

    • No seasonal adjustment is made

• 19. Comment

  • 19.1. Comment

    • Link to the "Consumer Price Index Manual. Theory and Practice":

      http://www.imf.org/external/pubs/ft/cpi/manual/2004/esl/cpi_sp.pdf