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.
The CPI covers all households in Spain, specifically the goods and services acquired by those households.
Households resident in family dwellings in Spain.
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.
The geographical scope constitutes all the national territory.
Brokendown information is calculated for the 52 provinces.
The survey is carried out monthly.
Results are available from January 1961.
The Base 2016 index series start January 2002. The Base 1992 index series cover from January 1961 to December 2001.
The base period or reference period of the index is the year 2016 (2016=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 2016 – 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.
For the year t, the calculation of CPI, base 2016, weights has been carried out using the data from the Household Budget Survey (HBS) 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.
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.
For each item or group of items, weights represent the corresponding percentage share of the total expenditure.
The data reference period is the month.
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 2017-2020, approved by Royal Decree 410/2016, of 31 October, is the Plan currently implemented. This statistical operation has governmental purposes, and it is included in the National Statistics Plan 2017-2020. (Statistics of the State Administration).
Order EHA/3411/2011, of 5 December 2011, sets out the new Consumer Price Index system, Base 2011.
In the case of the CPI, only aggregate information that does not allow obtaining information on microdata is published.
The CPI is disseminated monthly.
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.
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:
No information on microdata is provided for the CPI.
All information that may be provided on the CPI is available on the INE website.
- Base 2016:
Press release regarding the base change: http://www.ine.es/en/prensa/ipc_base_2016_en.pdf
- Base 2011:
Press release regarding the base change: http://www.ine.es/en/prensa/np701_en.pdf
- Base 2006:
Press release regarding the base change: http://www.ine.es/en/prensa/np446_en.pdf
- Base 2001:
Most important characteristics of the new system: http://www.ine.es/en/ipc01/index_en.html
The sections 11 to 19 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,
The Spanish CPI is a high-quality statistical operation. Its methodology follows the recommendations of the "Consumer Price Index Manual. Theory and Practice (2004)" 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.
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.
To adapt the CPI to these changes, 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 "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.
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.
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.
The INE has carried out general user satisfaction surveys in 2007, 2010, 2013 and 2016 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.
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 2016, is 100%.
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.
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.
During the entire statistical process, non-sampling errors are monitored.
There is no non-response rate in the CPI since the prices are collected in establishments by INE personnel. When a price is occasionally missing (the product is not available in the establishment during collection), estimation procedures are carried out.
Moreover, applications have been developed so as to detect and reduce the possible errors during price collection and recording.
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.
CPI results at all breakdown levels are published near day 13 of the month following the reference month.
Survey results are published according to the Short-term Statistics availability calendar of the INE ( http://www.ine.es/en/daco/daco41/calen_en.htm).
All CPI publications have been published on the date included in the availability calendar.
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.
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 2016.
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 2015, the length of the series of comparable data is 618 months.
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.
CPIs are internally coherent. Aggregations are carried out from the lowest geographical and functional information levels to the highest.
In the 2017 Annual Program, the estimate of the necessary budget appropriation to finance these statistics is 7.446,20 thousand euros.
There is no burden on respondents, since collection is carried out by INE interviewers.
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-.
CPI data is final the moment it is published for the first time and is therefore not subject to revision.
The data used for the compilation of the CPI is obtained from the direct collection of prices in the outlets.
Sample size consists in 479 consumption goods and services, for which around 220,000 prices are collected in approximately 33,000 outletsall over Spain.
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.
Price collection for the CPI is mainly carried out by means of a paper questionnaire.
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.
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.
- 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.
The main weighting sources of the CPI are the Household Budget Survey and the Spanish National Accounts.
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 the 479 items in each province.
- 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.
Any seasonal adjustment is made
Link to the "Consumer Price Index Manual. Theory and Practice":