1.1. Contact organisation
Statistics Netherlands (CBS)
1.2. Contact organisation unit
Government finance and consumer prices statistics department.
1.3. Contact name
Restricted from publication1.4. Contact person function
Restricted from publication1.5. Contact mail address
Statistics Netherlands
Henri Faasdreef 312 PO Box 24500
2492 JP The Hague 2490 HA The Hague
The Netherlands
1.6. Contact email address
Restricted from publication1.7. Contact phone number
Restricted from publication1.8. Contact fax number
Restricted from publication2.1. Metadata last certified
22 January 20252.2. Metadata last posted
22 January 20252.3. Metadata last update
22 January 20253.1. Data description
The harmonised index of consumer prices (HICP) is a consumer price index (CPI) that is calculated according to a harmonised approach. It measures the change over time of the prices of consumer goods and services acquired by households (inflation).
Due to the common methodology, the HICPs of the countries and European aggregates can be directly compared.
3.2. Classification system
European classification of individual consumption according to purpose (ECOICOP)
3.3. Coverage - sector
The HICP covers the final monetary consumption expenditure of the household sector as explained in the annex of the implementing regulation.
3.4. Statistical concepts and definitions
The main statistical variables are price indices.
3.5. Statistical unit
The basic unit of statistical observation are prices for consumer products.
3.6. Statistical population
See next points.
3.6.1. Statistical target population
The target statistical universe is the 'household final monetary consumption expenditure' (HFMCE) on the economic territory of the country by both resident and non-resident households. The household sector to which the definition refers, includes all individuals or groups of individuals irrespective of, in particular, the type of area in which they live, their position in the income distribution and their nationality or residence status. These definitions follow the national accounts concepts in the European System of Accounts.
3.6.2. Coverage error population
There are no deviations from the target population.
3.7. Reference area
See next points.
3.7.1. Geographical coverage
The HICP refers to the economic territory of a country as referred to in paragraph 2.05 of Annex A to ESA 2010, with the exception that the extraterritorial enclaves situated within the boundaries of a Member State or a country are included and the territorial enclaves situated in the rest of the world are excluded.
3.7.2. Coverage error regions
The HICP covers the entire economic territory of the country. The Caribbean Netherlands and the small part of the Netherlands known as the ‘Belgian enclave’ are not covered. The islands of Bonaire, St. Eustatius and Saba are special municipalities of the Netherlands. For these islands separate CPIs are calculated as of 2011. These are not included in the HICP.
3.8. Coverage - Time
See next points.
3.8.1. Start of time series
The HICP series started in January 1997.
3.8.2. Start of time series - national specifics
The HICP of Statistics Netherlands is included in the index as of 1996.
3.9. Base period
2015=100
The following units are used:
- Index point;
- Percentage change on the same period of the previous year (rates);
- Percentage change on the previous period (rates);
- Percentage share of the total (weights).
HICP is a monthly statistic.
6.1. Institutional Mandate - legal acts and other agreements
Harmonised Indices of Consumer Prices (HICPs) are harmonised inflation figures required under the Treaty on the Functioning of the European Union. Regulation (EU) 2016/792 of the European Parliament and the Council of 11 May 2016 (OJ L 135) sets the legal basis for establishing a harmonised methodology for the compilation of the HICP and the HICP-CT.
This regulation is implemented by Commission Regulation (EU) 2020/1148 of 31 July 2020.
Further methodological documentation, namely recommendations and guidelines, is available in the HICP dedicated section, under 'Methodology'.
6.2. Institutional Mandate - data sharing
Statistics Netherlands sends preliminary data to Eurostat for the HICP Flash estimate in each month of the year. These data have not been published yet at the moment of sending. Apart from that there is no advance data sharing.
7.1. Confidentiality - policy
Regulation (EC) No 223/2009 of the European Parliament and of the Council, of 11 March 2009, on the transmission of data subject to statistical confidentiality to the Statistical Office of the European Communities.
All data that are more detailed than the statistical results that are regularly published are considered confidential. This includes prices, article weights, outlet weights and product descriptions. Confidentiality must ensure that Statistics Netherlands does not publish data on prices or sales volumes for individual enterprises or products. The confidentiality of product descriptions must also ensure that products included in the CPI or their prices can be used as a benchmark for product pricing decisions by companies.
Confidentiality of data is regulated by the 'Wet op het Centraal Bureau voor de Statistiek'. Also the EU General Data Protection Regulation is there for the protection of personal data.
7.2. Confidentiality - data treatment
HICP outcomes are published on an aggregated level only. All information furnished by data suppliers is treated confidentially. No data from individual data suppliers can be deduced from published data or press releases.
In line with the Community legal framework and the European Statistics Code of Practice Eurostat disseminates European statistics on Eurostat's website (see point 10 - 'Accessibility and clarity') respecting professional independence and in an objective, professional and transparent manner in which all users are treated equitably. The detailed arrangements are governed by the Eurostat protocol on impartial access to Eurostat data for users.
8.1. Release calendar
The HICP is released according to Eurostat’s Release calendar.
The calendar is publically available and published at the end of the year for the full following year.
8.2. Release calendar access
Statistics Netherlands provides a schedule of CPI and HICP release dates well in advance (Publication calendar | CBS). In addition a weekly agenda, announcing press releases, is placed on the website of Statistics Netherlands every Friday.
8.3. Release policy - user access
The release of the final HICP and HICP-CT data is always accompanied by a news release. At the same moment of the news release, the detailed price index data are released on the publication database (StatLine). The figures are also available as open data in the form of datasets. By using web services, the most recent data can be retrieved, filtered and combined.
The HICP Flash estimate is published on StatLine at the same day as Eurostat releases the Flash estimate. The release of the HICP Flash estimate is accompanied by a news release and/or other (social) media exposure.
The press releases and detailed information are made public to all users at the same time. Press releases are announced well in advance via e.g. the publication calendar. There are no users that are granted special or pre-access to data.
Monthly.
10.1. Dissemination format - News release
The HICP data are published together with the CPI data every month in a press release which also contains explanatory notes. Next to that the data is also published in an online database called StatLine and via open data resources. When the press has any questions, they can contact our spokesperson via the press office. Other users can obtain information via the information service.
The HICP flash estimate is also published together with the CPI flash estimate, monthly in a press release and on StatLine. This dissemination is limited to the figures of the all items level and a selection of special aggregates.
All levels are published according to ECOICOP. The index figures are published with two decimals. The monthly and annual rate of change is published with one decimal. The figures and press releases are both disseminated in Dutch and in English.
Further methodology can be found at:
The CPI/HICP press release is published on a monthly basis. The press releases start with a short analysis of current outcomes and developments. They contain links to tables with time series for the overall CPI series, outcomes on a disaggregated level and international HICP figures. The releases also contain data on the contributions of disaggregated levels to the overall CPI. Apart from the press release the results are also published in the statistical bulletin, a monthly publication of Statistics Netherlands.
The release of the CPI and HICP flash estimates is also accompanied by a press release and/or other social media exposure.
10.2. Dissemination format - Publications
The Dutch HICP is published in several national publications. Publications are disseminated on the website of Statistics Netherlands and also in the statistical bulletin and StatLine.
The Dutch Central Bank and the CPB Netherlands Bureau of Economic Policy Analysis include the HICP in their forecasts.
10.3. Dissemination format - online database
Detailed HICP time series are available on the HICP database as well as on the database of Statistics Netherlands.
Detailed information about the HICP and HICP-CT can be found via HICP 2015 = 100.
Detailed information about the contributions and impact on HICP and HICP-CT can be found via HICP 2015 = 100, detailed contributions and impact to the headline figure.
10.4. Dissemination format - microdata access
Generally speaking micro data is not available for the general public. However, in exceptional cases anonymised micro data can be accessed by admitted third parties on request by using remote access. Detailed transaction data cannot be shared with third parties.
10.5. Dissemination format - other
The HICP is disseminated on Eurostat's HICP website.
10.6. Documentation on methodology
The Harmonised Index of Consumer Prices (HICP) Methodological manual – 2024 edition provides the reference methodology for the production of HICP.
10.6.1. Documentation on methodology - national specifics
The Dutch methodological notes on the HICP are published at Centraal Bureau voor de Statistiek | CBS.
- More information about the yearly base shift (in Dutch)
- Methodological report on consumer prices (in Dutch)
- Harmonized consumer price index 2015=100
- Calculation of contributions and impacts
- The impact of the corona crisis on compiling the CPI
- The consequences of the corona crisis for the weight scheme (in Dutch)
- Processing energy prices for the consumer price index
10.7. Quality management - documentation
There are no publicly available quality related documents.
Statistics Netherlands is certified according to ISO 9001 standards. The certification confirms that Statistics Netherlands fulfills the quality requirements for statistics production.
Also Statistics Netherlands follows the European statistics code of practice.
European statistics code of practice
11.1. Quality assurance
See next points.
11.1.1. Quality management - Compliance Monitoring
11.1.2. Quality assurance - national specifics
Statistics Netherlands is certified according to ISO 9001. In practical terms for the HICP, this means:
- all activities are documented.
- documents, software and data files are well-structured and in order.
- checks are carried out in critical process steps.
- continuous improvement is integrated as a routine in the daily work: internal quality revisions assures the compliance to the ISO-standards.
- issues are documented using the PDCA-method (plan, do, check, act).
A separate team of people checks the figures and after that the results are checked by an independent person who is not directly involved in the production of HICP.
11.2. Quality management - assessment
See next points.
11.2.1. Compliance monitoring - last report and main results
The last available compliance or follow-up report can be found in Eurostat's web page: Quality - Harmonised Indices of Consumer Prices (HICP) - Eurostat (europa.eu).
11.2.2. Quality assessment - national specifics
The quality of the HICP can be assumed to be very high. Its concepts and methodology have been developed according to international standards and using consumer price statistics experience from all EU Member States. HICPs are considered to be sufficiently accurate for all practical purposes they are put into. In particular it is the best measure of inflation for the euro area and European Union as a whole as well as for the comparisons of inflation across countries for which it is compiled. The indices are disseminated around the first week of the month following a predetermined timetable.
Further work is ongoing to improve the quality and in particular the comparability of the index. Key priorities are the treatment of owner-occupied housing (currently excluded) and greater harmonisation of methods for quality adjustment and sampling.
The HICP in the Netherlands is subject to an internal audit once every three years. There is a yearly ISO 9001 audit for the whole department.
12.1. Relevance - User Needs
In addition to being a general measure of inflation, the HICP is also used in the areas of:
- wages, social benefit and contract indexation;
- economic forecasting and analysis;
- measuring specific price trends;
- accounting purposes and deflating other series;
- inflation targeting by central banks;
- cross-country economic comparisons.
The euro area (evolving composition) index is used by the European Central Bank (ECB) as the main indicator for monetary policy management. The ECB and the European Commission's Directorate-General for Economic and Financial Affairs (DG ECFIN) use the HICP for assessing price stability and price convergence required for entry into European Monetary Union.
Other users include: National Central Banks, financial institutions, economic analysts, the media and the public at large.
12.1.1. User Needs - national specifics
The HICP/CPI figures are mostly used for:
- Wage indexations (by e.g. private companies),
- Pension indexations (pension funds),
- Rent indexations (landlords),
- Inflation monitoring (Central bank),
- Research (planning agencies and universities).
12.2. Relevance - User Satisfaction
There is no user satisfaction survey available. The most important users of HICP data are represented in the so-called Macroeconomic Advisory Board (Adviesraad Macro-economische statistieken). This board meets on a yearly basis to give their views on HICP related topics.
12.3. Completeness
All ECOICOP indices at 5-digit level are disseminated above the weight limit of 1/1000.
13.1. Accuracy - overall
The accuracy of HICP is generally considered to be high. The accuracy of source data is monitored by assessing the methodological soundness of price and weight sources and the adherence to the methodological recommendations. There is a variety of data sources both for weights (National Accounts data, Household Budget Survey data, etc.) and prices (web scraping, transaction data, registrations, online surveys and central collection via the internet are used). The type of survey and the price collection methods ensure sufficient coverage and timeliness. The outlets, from which prices are collected, are chosen to represent the existing trade and services network and they are based usually on three main criteria: popularity with consumers; significant turnover from consumer sales; and availability of goods and services included in the HICP basket. All the private households in the economic territory of the country are covered, whether resident or not and irrespective of their income.
Furthermore, Eurostat and the Member States are actively following up an Action Plan concerning quality adjustment and sampling issues. Concrete best practices have been agreed for a range of specific goods and services (in particular cars, consumer durables, books and CDs, clothing and computers).
13.2. Sampling error
The sampling errors are reduced by using a sample of consumer prices that is as large as possible, given resource constraints.
13.3. Non-sampling error
For the HICP non-sampling errors are not quantified. They are reduced through continuous methodological improvements and survey process improvements, which can help avoiding coding and typing errors.
14.1. Timeliness
The full set of HICPs is published each month according to a pre-announced schedule, usually between 15 and 18 days after the end of the reference month. Each year, the January news release is published at the end of February to allow for the annual update of the weights of individual product groups and the relative country weights of Members States in the country-group aggregates.
The euro area flash estimate is published on the last working day of the reference month or shortly after that.
14.2. Punctuality
Since the March 1997 launch of the HICP release, the HICP for the country groups aggregates has always been published on the pre-announced release dates.
15.1. Comparability - geographical
HICPs across Member States aim to be comparable. Any differences at all levels of detail should only reflect differences in price changes or expenditure patterns.
To this end, concepts and methods have been harmonised by means of legislation. HICPs that deviate from these concepts and methods are deemed comparable if they result in an index that is estimated to differ systematically by less than or equal to 0.1 percentage points on average over one year against the previous year (Article 4 of Council and Parliament Regulation (EU) 2016/792).
15.2. Comparability - over time
There have been several improvements in methodology since HICP was introduced with the aim of improving reliability and comparability of the HICP. These changes may have introduced breaks in time series. Notable changes were the following:
- In January 2011 there is a break in the series due to new methods to compile price indices for package holidays and airline tickets.
- In April 2018 a level adjustment for clothing was carried out. Detailed information is available on the website of Statistics Netherlands
- In June 2023 a new method for calculating energy prices has been introduced in the HICP. Detailed information is available on the website of Statistics Netherlands.
15.3. Coherence - cross domain
Differences between CPI and HICP
CPI and HICP are different in certain aspects. This section will in short summarise the differences. They can be subdivided into four themes:
- Target population; which consumers and which transactions are included in the index,
- Coverage; which consumption expenditures are included,
- Price definition; how are some prices defined,
- Classification.
Target population
This theme covers two subjects:
- The CPI uses a national concept, whereas the HICP uses a domestic concept,
- Consumption by institutional households.
The national concept of the CPI implies that all expenditures of consumers living in the Netherlands are included, regardless of whether these expenditures are in the Netherlands or abroad.
The domestic concept of the HICP implies that expenditures abroad of consumers living in the Netherlands are excluded from the HICP, but that expenditures of foreign visitors on Dutch territory are included.
Expenditures by people living in institutional households are included in the HICP. In the 2006=100 series these expenditures were excluded from the CPI. Starting from the 2015=100 series expenditures by people living in institutional households are included in the CPI excluding the own contributions that these people pay for living in the institution.
Coverage
Three groups of goods and services are included in the CPI but excluded from the HICP:
- Imputed rentals for housing,
- Contributions,
- Consumption related taxes.
For households renting a house, the rents payments are included in CPI and HICP. For households living in a house of their own imputed rentals for housing is included in the CPI and the developments of imputed rentals contribute to the CPI results. Owner occupied housing expenditures are excluded from the HICP.
The HICP does not consider subscriptions or contributions for recreational and sports clubs, labour unions and other NPISHs to be consumption expenditures, but considers it to be transfers. Consumption related taxes are also out of the scope of the HICP. Government services are included. On the other hand, own contributions paid for living in an institutional household are included in the HICP, but excluded from the CPI.
Price definition
For some product categories price definitions in HICP and CPI differ. There are differences in the treatment of parents’ contributions for child care. In the CPI the gross price for child care is observed. As a consequence, the weight for child care is high. In the HICP only the parents’ own contributions are included. Contributions that the government pays to the parents are deducted from the gross price. Therefore, the weights for child care are also lower. Finally, changes in own contributions for health care that is covered in the basic health insurance are treated differently. If a certain element of health care is taken out of the coverage of the base policy and the consumer has to pay for that care himself, this is reflected in the CPI only by an increase of the weight for health care. Likewise, a change whereby previously uninsured health care is taken up in the base policy also does not lead to a decrease of the CPI.
In the HICP, changes in the basic insurance policy are treated as price changes. A change whereby insured health care from a certain point in time is no longer covered by basic health insurance and for which the consumer must pay an own contribution is treated as a price increase from zero to the new own contribution or market price. Alternatively a change whereby a part of health care that was not insured is brought under the coverage of the basic health insurance is treated in the HICP as a price decrease from the existing price or own contribution to zero.
Classification
Differences in classification all have to do with product groups that are out of the scope of one of the two series.
Included in the CPI, but not included in the HICP are:
- ECOICOP 04.2.1 Imputed rentals for housing,
- ECOICOP 09.4.1.3 Membership sports and recreation clubs,
- ECOICOP 13 Consumption related taxes,
- ECOICOP 14 Consumption abroad.
Included in the HICP, but not in the CPI are:
- ECOICOP 12.4.0.2 Retirement homes for elderly persons and residences for disabled persons.
15.4. Coherence - internal
The HICPs are internally coherent. Higher level aggregations are derived from detailed indices according to well-defined procedures.
Not available.
17.1. Data revision - policy
The HICP series, including back data, is revisable under the terms set in Articles 17-20 of Commission Implementing Regulation (EU) 2020/1148.
17.1.1. Data revision - policy - national specifics
When errors are discovered or if new information leads to new results that have significant impact especially on the level of headline inflation, then all HICPs concerned are revised. Weights will not be revised if new data from the National Accounts become available.
Revision of CPI and HICP figures takes place in the following cases:
- If the impact on the annual rate of change of the CPI or HICP is 0.1 percentage points or more;
- If the HICP uses sources that are also used for compiling other, independent statistics, the HICP follows in principle the revision of these statistics. Examples of this are the rents and fuel prices.
The following additional comments can be made here:
- It does not matter for the review whether the published figures are provisional or final.
- The 0.1 percentage point impact counts as an absolute value for unrounded figures.
- If the CPI is revised, the HICP is also revised, and vice versa.
- Figures with a generally known, fixed starting date (such as tuition, public transport, municipal taxes) are not corrected (revised) with retrospective information, but are updated in the reporting month in which the new information arrives, unless the impact is 0.1 percentage points or more. In case the concerned figures are still flagged as provisional, they can also be brought to the correct level if the impact is below 0.1 percentage points.
17.2. Data revision - practice
Index numbers may be revised in the case of errors or when improved information leads to a significant change. A base-year revision does not lead to the backward revision of results. Statistics Netherlands has revised our HICP in the past ten years.
The most important revision is the implementation of a new method for package holidays and passenger transport by air. The HICP headline inflation was affected (by between 0.1 and 0.3 percentage points) as well as the all items index and indices for passenger transport by air and package holidays for the months in the year 2011. The revisions for package holidays improved the accuracy of the HICP because in the new method real transaction prices are used versus list prices in the former method. The timing of the price changes according to Commission regulations was obviously also an improvement. Together with the revision a level adjustment was carried out by January 2011.
Also in April 2018 a level adjustment for clothing was carried out. For all details concerning this adjustment, see CPI – Level adjustment price index clothing April 2018 | CBS.
Next to these revisions there is yearly a small revision of the HICP in July due to incomplete data for the rents at the moment of first publication. The first publication of the HICP of July is always flagged as provisional for this reason. The revision is usually small, since 2016 the difference between the provisional and the final publication has not exceeded an 0.1 index point on the ECOICOP level for 04.1 - Actual rentals for housing.
Furthermore, the first publication of the HICP in January is always flagged as provisional, because in January there is an increased chance that not all source data is available at the moment of the first publication. If new data becomes available afterwards, the January figures can then still be revised. This was done in 2023 for categories 04.4.2 - Refuse collection and 04.4.3 - Sewerage collection. This revision had an impact below 0.1 percentage points on the all items level.
18.1. Source data
See next points.
18.1.1. Weights
The basis for determining the expenditure shares in 2023 is formed by the provisional consumption figures of the 2022 National Accounts. The amounts from the National Accounts are classified differently than in the HICP. The amounts according to this National Accounts classification are distributed according to the classification of HICP article groups (ECOICOP groups) using a correspondence table.
The weights used in 2024 approximates consumer spending in 2023. Significant changes in expenditure shares between 2022 and 2023 are updated in the amounts from the National Accounts for 2022. This is done in all categories. For the weights of the 2024 reporting year, the growth rate of the average of the first three quarters of 2023 compared to the first three quarters of 2022 has been added to the results.
For certain product groups, such as food, package holidays abroad, airline tickets and restaurants, additional data up to and including December 2023 have been used to better estimate the fourth quarter of 2023 and to check the results. Also turnover statistics up to and including October 2023 were used to check the figures.
The fourth quarter of 2023 is integrated by using the above-mentioned data. If no additional information was available, the growth rate of the first three quarters of 2023 compared to the first three quarters of 2022 was used instead to estimate the fourth quarter. When fourth quarter information was used, it replaced the growth rate of the first three quarters and the growth rate of 2023 compared by 2022 was added to the results.
Statistics Netherlands uses weights below the level of sub-index level for outlet types and articles. In addition and where possible, a weight is also allocated for the market share of the companies. The lowest level of aggregation is the level of outlet types and articles (7-digit). The source of these weights are obtained by transaction data and market research.
The weights are price-updated.
18.1.1.1. Compilation at elementary aggregate level
Statistics Netherlands uses weights below the level of sub-index level for outlet types and articles. In addition and where possible, a weight is also allocated for the market share of the companies. The lowest level of aggregation is the level of outlet types and articles (7-digit). For the outlets from which we receive transaction data, we use this data for outlet and product weights. For other outlets we use a combination of retail statistics and market research to determine weights. Most weights applied at the elementary aggregate level are updated yearly. There are no regional weights in the Dutch HICP.
18.1.1.2. List of elementary aggregates
Restricted from publication18.1.1.3. Compilation of sub-index weights
Restricted from publication18.1.1.4. Price updating
Statistics Netherlands has applied price updating to make the expenditure shares representative for December t-1. We do this according to the guidelines by dividing the December price index by the average price index of the past year. This factor is multiplied with the value of the National Accounts data. The price update has been carried out at the level of the sub-index and outlet.
Statistics Netherlands has not applied price updating from year t-2 to year t-1 as 2023 expenditures were already taken into account.
18.1.2. Prices
The price data is based on a mix of multiple data sources: survey data, administrative data sources, transaction data and web-scraped data.
18.1.2.1. Prices Data Source – detailed information
Restricted from publication18.1.2.2. Price Collection Survey
Restricted from publication18.1.2.3. Administrative data sources
Restricted from publication18.1.2.4. Transaction data - general information
Transaction data was introduced in the HICP in 2002.
Statistics Netherlands processes transaction data for these types of retailers:
- Drugstores
- Consumer electronics
- Liquor stores
- Motorfuels
- DIY stores
- Supermarkets
- Department stores
- Travel agencies
- Internet shops
- Garden centers
- Shoe stores
- Clothing stores
- Household stores
- Energy suppliers
An increase in coverage is planned for clothing stores.
For details on products and categories, see the inventory detail annex under 19.2 (restricted to Eurostat).
18.1.2.5. Transaction data - detailed information
In most cases the first two or three full weeks of the month are used for the calculation of transaction data price indices. The number of weeks remains the same over time.
Statistics Netherlands uses the following steps to produce the index:
- Basic technical checks on the file
- Import data into the database
- Checks on turnover and number of GTINs
- Maintenance of classifications
- Computation
- Analysis and validation of indices
- Publication
Most of the retailers files contain information on article group level. Each article group is mapped to a specific ECOICOP group (if possible). Each GTIN within those groups is included in the calculation.
The average price per GTIN is determined by adding up all the sales and the units sold and dividing each other. This is usually aggregated to an elementary aggregate via the Quality Adjusted Unit Value - Geary Khamis index method (QU-GK). For most categories, the window length is a maximum of 13 months and fixed base expanding window is used, starting in December. For some categories, a rolling time window with a length of 25 months is used.
The index calculation of the level above the elementary aggregate is calculated in the same way as all other products. QU-GK treats missing GTINs as unavailable products. Each relaunched and replaced GTIN is immediately added to the calculation. Resampling takes place each month according to QU-GK.
After calculation, the price indices are checked on the level of retailer x ECOICOP group. If these indices fall outside a certain bandwidth, development of individual GTINs is checked for correctness of the prices.
In case transmissions do not arrive in time, the corresponding elementary aggregates can be imputed following a standard procedure.
In addition to QU-GK, Statistics Netherlands also uses a number of other methods. For example, we use the transaction data in a traditional way (GTINs as individual representatives for an item). A Jevons method is also applied.
18.1.2.6. Web scraping - general information
Web scraping was introduced in the HICP in 2015.
Web scraping is used to gather online price data from clothing and footwear retailers, furniture stores, wireless telephone services and bundled telecommunication services on a daily or weekly basis. The percentage of weight covered by web-scraped data for clothing is 33% in men, 32% in women and 31% in children; 67% for other clothing articles; for footwear the percentage of weight is 27% in men, 26% in women and 28% in children; 10% for household furniture; 18% for other furniture and furnishings; and 100% for wireless telephone services and bundled telecommunication services.
There are no plans to increase the coverage of web scraping. No foreign websites are scraped.
Web scraping is used both to represent e-commerce (online shopping) and as a proxy for physical shop price collection.
18.1.3. Sampling
See next points.
18.1.3.1. Sampling design: locations for survey
All regions of the Netherlands are in the sample. The sample contains cities, small towns and villages. The sample is updated continually.
18.1.3.2. Sampling design - outlets
The outlet selection is decided upon centrally. Outlets in the whole country are chosen for the survey. They are identified by the commodity specialists of our organization based on the Household Budget Survey and other market research.
Electronic questionnaires are sent to canteens, cafés, movers, funeral businesses, notaries, opticians, sport shops, flower shops and several other business types.
In 2024, tobacco shops have been added to the sample, because tobacco products cannot be sold in supermarkets anymore.
18.1.3.3. Sampling design - products
Restricted from publication18.1.3.4. Sampling design: newly significant goods and services
Restricted from publication18.2. Frequency of data collection
Price data are collected every month.
18.3. Data collection
See next points.
18.3.1. Timing of price collection
Price collection is done in the first three weeks of the month.
18.3.2. Devices for price collection
We do not do physical price collection. Questionnaires are filled in electronically.
18.4. Data validation
The price data are checked for internal consistency and completeness. When necessary, action is taken to verify the data. If the data are correct, the price indices are calculated and the results are verified and validated. Validation is done by members of the team who are not directly involved in processing the price data, and therefore have an independent perspective.
18.4.1. Data validation - Survey data
The data is checked for internal consistency and completeness. Data entry errors are checked by the employee when the prices are entered into the computer. If the price differs from the previous price, the employee needs to fill in the reason for the differences. The consistency of the price information over time is monitored by following the same item for as long as being representative. Where necessary, additional price information will be noted so that this can be included next time. When observing an item, it must always remain within the framework of the price information that has been drawn up for the item. When extreme prices or price changes are observed, it is checked whether the price is correct and whether the price change can be explained. If necessary, this is corrected or the employee who noted the prices is alerted to this.
A price quote may be considered an outlier if the price level or the price change is significantly higher or lower than other price quotes and price changes for the same product. An outlier is first checked for correctness of the registration (price entered in database = price as it is collected) and the price collector may add an explanation for an extreme price (change). Exceptionally the outlet may be contacted to confirm the price quote. On the basis of all information the price may be corrected, accepted or in few cases rejected. The range of acceptable prices differs according to the product type and description (wide or tight). Prices are rejected only if the price quote is considered an erroneous observation or a price observation of a product that is not in conformity with the product description. Outlier detection is used. Prices that are more than 850 percent higher or 85 percent lower than the average price of the item are automatically excluded from the calculation. Prices that deviate more than 15 percent from the previous price must be accompanied by a statement.
18.4.2. Data validation - transaction data, web scraping and large administrative data
For transaction data, the price indices are checked at the level of retailer x ECOICOP group. If these indices fall outside a certain bandwidth, development of individual GTINs is checked for correctness of the prices. The source data is also checked for consistency, among others based on turnover.
The approach to validate web-scraped data is divided in several steps. On a daily basis each data file per retailer is globally checked on discrepancies in availability, file size and risen errors during the web scraping process. Twice a week the web-scraped data per retailer from the previous couple of days is checked on amount of GTINs and categories. After each week our analysts evaluate which data files can be included for further processing. After the price indices are calculated on the level of retailer x ECOICOP group, they are checked as well.
The validation procedures for administrative data are comparable with the procedures for survey data.
18.4.3. Data validation - weights
On various moments in the process of making the weighting scheme, the plausibility of the weights is checked. Data on household expenditure of the National Accounts department, which is used as input for the HICP weighting scheme, is compared to the same data that was provided in the previous year. The most notable absolute and relative changes are subsequently presented to experts of the National Accounts department and have to be clarified by them. If the first version of the HICP weighting scheme is made, it is subjected to an extensive review. Members of the review committee consist of experts from within the HICP/CPI team, as well as experts from the National Accounts department.
Throughout the year, commodity specialists of the HICP/CPI team make weighting matrices for the lowest level ECOICOP groups. These matrices indicate the relative weights on the level of item and outlet type for the coming calendar year and they are accompanied by a report that explains how both the choice of the items and the distribution of the weights have been established. In order to achieve that, the commodity specialists conduct market research, using data from different sources such as retail statistics, household budget surveys and trade associations. The weighting matrices as well as the report that goes with it, are reviewed by experts within the HICP/CPI team.
18.4.4. Indices
Statistics Netherlands validates the indices top-down. Here, the impact on the total figure and the change compared to last year and last month is examined. If the impact is relatively large, it is investigated which elementary aggregates are the main cause of the change. We will then further investigate these indices. Then we compare the index with the index level of recent years. The changes in the index are checked to see if they match the expectations. We also look at the underlying reason why the index has the relevant level. Where necessary, prices are checked again and the steps of 18.4.1 are carried out.
18.5. Data compilation
See next points.
18.5.1. Elementary price index formulae
The HICP is compiled as a Laspeyres-type index. For most elementary aggregates a Dutot-index is compiled. In the case of transaction data, Statistics Netherlands uses mostly QU-GK. A Jevons method is also applied for transaction data. For web-scraped data we use unit value.
Price observations are not rounded but entered in cents. The HICP-weights (1/1000) are disseminated using two decimal places (smallest unit is 1/100000). All calculations are performed without any rounding in the calculation process. The index results are rounded to two decimal places at the point of publication. Annual rates and monthly rates of change are calculated from the published figures and then rounded to one decimal place for publication.
18.5.2. Aggregation of different data sources
We use Dutot for aggregation from representative to elementary aggregates for survey data. For most transaction data we use QU-GK. For web-scraped data we use unit value calculation. From the elementary aggregate a Laspeyres-type index upwards is applied.
18.5.3. Chaining, linking and splicing methods
Each December a new unchained index series December Y=100 is started, using updated baskets and new weights. At each level of detail the January 'long series' index (published series) is calculated as Index (January, new unchained series)/100 * Index (December, long series).
Splicing is used for a part of the transaction data. A 25-month window with Half Year reference Chained Splice (HYCS) is applied.
18.5.4. Quality adjustments and replacements
Restricted from publication18.5.5. Seasonal items
ECOICOPs for fish, fruit, vegetables, flowers, clothing, footwear and package holidays are considered seasonal products groups. For these aggregates a strict annual weights method is used. The weights of the in-season products are the same every in-season month.
18.6. Adjustment
See next point.
18.6.1. Seasonal adjustment
The HICP is not seasonally adjusted.
None.
The harmonised index of consumer prices (HICP) is a consumer price index (CPI) that is calculated according to a harmonised approach. It measures the change over time of the prices of consumer goods and services acquired by households (inflation).
Due to the common methodology, the HICPs of the countries and European aggregates can be directly compared.
The main statistical variables are price indices.
The basic unit of statistical observation are prices for consumer products.
See next points.
See next points.
HICP is a monthly statistic.
The accuracy of HICP is generally considered to be high. The accuracy of source data is monitored by assessing the methodological soundness of price and weight sources and the adherence to the methodological recommendations. There is a variety of data sources both for weights (National Accounts data, Household Budget Survey data, etc.) and prices (web scraping, transaction data, registrations, online surveys and central collection via the internet are used). The type of survey and the price collection methods ensure sufficient coverage and timeliness. The outlets, from which prices are collected, are chosen to represent the existing trade and services network and they are based usually on three main criteria: popularity with consumers; significant turnover from consumer sales; and availability of goods and services included in the HICP basket. All the private households in the economic territory of the country are covered, whether resident or not and irrespective of their income.
Furthermore, Eurostat and the Member States are actively following up an Action Plan concerning quality adjustment and sampling issues. Concrete best practices have been agreed for a range of specific goods and services (in particular cars, consumer durables, books and CDs, clothing and computers).
The following units are used:
- Index point;
- Percentage change on the same period of the previous year (rates);
- Percentage change on the previous period (rates);
- Percentage share of the total (weights).
See next points.
See next points.
Monthly.
The full set of HICPs is published each month according to a pre-announced schedule, usually between 15 and 18 days after the end of the reference month. Each year, the January news release is published at the end of February to allow for the annual update of the weights of individual product groups and the relative country weights of Members States in the country-group aggregates.
The euro area flash estimate is published on the last working day of the reference month or shortly after that.
HICPs across Member States aim to be comparable. Any differences at all levels of detail should only reflect differences in price changes or expenditure patterns.
To this end, concepts and methods have been harmonised by means of legislation. HICPs that deviate from these concepts and methods are deemed comparable if they result in an index that is estimated to differ systematically by less than or equal to 0.1 percentage points on average over one year against the previous year (Article 4 of Council and Parliament Regulation (EU) 2016/792).
There have been several improvements in methodology since HICP was introduced with the aim of improving reliability and comparability of the HICP. These changes may have introduced breaks in time series. Notable changes were the following:
- In January 2011 there is a break in the series due to new methods to compile price indices for package holidays and airline tickets.
- In April 2018 a level adjustment for clothing was carried out. Detailed information is available on the website of Statistics Netherlands
- In June 2023 a new method for calculating energy prices has been introduced in the HICP. Detailed information is available on the website of Statistics Netherlands.