- Methods and Projects
- Standards and Classifications
Standardised Methodological Report
Consumer Price Index (CPI)
- 1Contact
- 1.1Contact organisation
National Statistics Institute of Spain
- 1.5Contact mail address
Avenida de Manoteras 50-52 - 28050 Madrid
- 1.1Contact organisation
- 2Metadata update
- 2.1Metadata last certified
26/03/2024
- 2.2Metadata last posted
15/02/2024
- 2.3Metadata last update
26/03/2024
- 2.1Metadata last certified
- 3Statistical presentation
- 3.1Data 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.
- 3.2Classification 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 - Rúbricas IPC
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
32 Reparación de calzado
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
- Comunidades y Ciudades Autónomas
- 3.3Sector coverage
The CPI covers all households in Spain, specifically the goods and services acquired by those households.
- 3.4Statistical 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.
- Adjustment due to change in quality
- 3.5Statistical unit
Households resident in family dwellings in Spain.
- 3.6Statistical 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.
- 3.7Reference area
The geographical scope constitutes all the national territory.
Brokendown information is calculated for the 52 provinces.
- 3.8Time 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.
- 3.9Base 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.
- 3.1Data description
- 4Unit of measure
- 4.1Unit 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.
- 4.1Unit of measure
- 5Reference period
- 5.1Reference period
The data reference period is the month.
Data referred to the period: Mensual A: 2024 MES: 01
- 5.1Reference period
- 6Institutional mandate
- 6.1Legal 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 2021-2024, approved by Royal Decree 1110/2020, of 15 December, is the Plan currently implemented. This statistical operation has governmental purposes, and it is included in the National Statistics Plan 2021-2024. (Statistics of the State Administration).
Order EHA/3411/2011, of 5 December 2011, sets out the new Consumer Price Index system, Base 2011.
- 6.2Data 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.
- 6.1Legal acts and other agreements
- 7Confidentiality
- 7.1Confidentiality - 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
- 7.2Confidentiality - 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.
- 7.1Confidentiality - policy
- 8Release policy
- 8.1Release calendar
The advance release calendar that shows the precise release dates for the coming year is disseminated in the last quarter of each year.
- 8.2Release calendar access
The calendar is disseminated on the INEs Internet website (Publications Calendar)
- 8.3User 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
- 8.1Release calendar
- 9Frequency of dissemination
- 9.1Frequency of dissemination
The CPI is disseminated monthly.
- 9.1Frequency of dissemination
- 10Accessibility and clarity
- 10.1News 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
- 10.2Publications
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.
- 10.3On-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:
Number of entries in 2023 was
- Number of entries to data bases AC1=4,022,845
- Number of entries to metadata bases AC2=7,478 - 10.4Micro-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.
- 10.5Other
All information that may be provided on the CPI is available on the INE website.
- 10.6Documentation 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%
- 10.7Quality 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.
- 10.1News release
- 11Quality management
- 11.1Quality 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.
- 11.2Quality 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:
- Collection of information using electronic devices.
- 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.
- 11.1Quality assurance
- 12Relevance
- 12.1User 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.
- 12.2User 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.
- 12.3Completeness
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%.
- 12.1User needs
- 13Accuracy and reliability
- 13.1Overall 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.
- 13.2Sampling 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.
- 13.3Non-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 2023 the average item non-response rate is A5 = 3.90%.
Moreover, applications have been developed so as to detect and reduce the possible errors during price collection and recording.In year 2023, the average imputation rate is A7 = 1.93%.
- 13.1Overall accuracy
- 14Timeliness and punctuality
- 14.1Timeliness
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
- 14.2Punctuality
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%.
- 14.1Timeliness
- 15Coherence and Comparability
- 15.1Comparability - 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.
- 15.2Comparability - 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 2023, the length of the series of comparable data is CC2=714 months.
- 15.3Coherence - 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.
- 15.4Coherence - internal
CPIs are internally coherent. Aggregations are carried out from the lowest geographical and functional information levels to the highest.
- 15.1Comparability - geographical
- 16Cost and burden
- 16.1Cost and burden
In the 2024 Annual Program, the estimate of the necessary budget appropriation to finance these statistics is 7,655.03 thousand euro.
There is no burden on respondents, since collection is carried out by INE interviewers.
- 16.1Cost and burden
- 17Data revision
- 17.1Data 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-.
- 17.2Data revision - practice
CPI data is final the moment it is published for the first time and is therefore not subject to revision.
- 17.1Data revision - policy
- 18Statistical processing
- 18.1Source 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 493 consumption goods, whose prices are obtained by scanner data.
- 18.2Frequency 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.
- 18.3Data 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.
- 18.4Data 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.
- 18.5Data 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.
- 18.6Adjustment
No seasonal adjustment is made
- 18.1Source data
- 19Comment
- 19.1Comment
Link to the "Consumer Price Index Manual. Theory and Practice":
http://www.imf.org/external/pubs/ft/cpi/manual/2004/esl/cpi_sp.pdf
- 19.1Comment