Harmonised index of consumer prices (HICP) (prc_hicp)

National Reference Metadata in Euro SDMX Metadata Structure (ESMS)

Compiling agency: National Statistical Institute of Bulgaria.

Time Dimension: 2020-A0

Data Provider: BG1

Data Flow: HICP_NES_A


Eurostat metadata
Reference metadata
1. Contact
2. Metadata update
3. Statistical presentation
4. Unit of measure
5. Reference Period
6. Institutional Mandate
7. Confidentiality
8. Release policy
9. Frequency of dissemination
10. Accessibility and clarity
11. Quality management
12. Relevance
13. Accuracy
14. Timeliness and punctuality
15. Coherence and comparability
16. Cost and Burden
17. Data revision
18. Statistical processing
19. Comment
Related Metadata
Annexes (including footnotes)
 



For any question on data and metadata, please contact: EUROPEAN STATISTICAL DATA SUPPORT

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1. Contact Top
1.1. Contact organisation

National Statistical Institute of Bulgaria.

1.2. Contact organisation unit

Consumer Prices, Housing prices and PPP Department.

1.5. Contact mail address

2, P. Volov Str.
1038 Sofia, Bulgaria


2. Metadata update Top
2.1. Metadata last certified 01/07/2020
2.2. Metadata last posted 15/01/2021
2.3. Metadata last update 01/07/2020


3. Statistical presentation Top
3.1. Data description

The harmonised index of consumer prices (HICP) is a consumer price index (CPI) that is calculated according to a common approach. It measures the change over time of the prices of consumer goods and services acquired by households. Because of 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.

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

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

No deviations from the target population.

3.7. Reference area

3.7.1. Geographical coverage

The HICP refers to the economic territory of a Member State as defined by ESA2010.

3.7.2. Coverage error regions

Bulgaria has no overseas territories. The economic territory of Bulgaria consists of the geographic territory. The HICP covers the entire economic territory consistent with NA. The NA estimates follow the definitions laid down in ESA2010.

No parts of the economic territory of Bulgaria are excluded from the index.

3.8. Coverage - Time

3.8.1. Start of time series

In accordance with Council Regulation (EC) No 1687/98, each Member State is required to produce a harmonised index of consumer prices (HICP) starting in January 1997.

3.8.2. Start of time series - national specifics

See the HICP database

January 1997

3.9. Base period

2015=100


4. Unit of measure Top

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).


5. Reference Period Top

HICP is a monthly statistics.


6. Institutional Mandate Top
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. Council Regulation (EC) No 2016/792 of 11 May 2016 (OJ L 135) sets the legal basis for establishing a harmonised methodology for the compilation of the HICP, the MUICP and the EICP.
The Commission has brought forward detailed Regulations establishing the specific rules governing the production of harmonised indices.

 

Regulations:

  • Initial implementing measures (1749/1996)
  • Sub-indices (2214/1996)
  • Weights (2454/1997)-repealed
  • Coverage of goods and services (1687/1998)
  • Geographic and population coverage (1688/1998)
  • Treatment of tariffs (2646/1998)
  • Treatment of insurance (1617/1999)
  • Revised sub-indices (1749/1999)
  • Treatment of products in the health, education and social protection sectors (2166/1999)
  • Timing of entering purchaser prices (2601/2000)
  • Treatment of price reductions (2602/2000)
  • Treatment of service charges (1920/2001)
  • Minimum standards for revisions (1921/2001)
  • Common index reference period (1708/2005)
  • Temporal coverage of price collection (701/2006)
  • Sampling (1334/2007)
  • Seasonal products (330/2009)
  • Weights (1114/2010)
  • Owner-occupied housing (93/2013)
  • Common index reference period (2015/2010)

 

All relevant regulations as well as further methodological details can be found in the HICP section on Eurostat's website under Methodology => Legislation.

6.2. Institutional Mandate - data sharing

None.


7. Confidentiality Top
7.1. Confidentiality - policy

Legal basis:

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;

Law on statistics

The confidentiality of the HICP data set is treated in respect of national legislation: Law of Statistics, Chapter Six ‘Protection of secrecy’, Articles 25, 26, 26a, 27 and 27a. Art. 25 stipulates that individual data (‘individual data’ are data about a specific statistical unit) received and collected through statistical surveys shall constitute a statistical secret and may be used only for statistical purposes. Individual data received for the purposes of statistical surveys may not be used as evidence before the bodies of the executive and the judiciary.

The NSI and statistical authorities and their staff may not disclose or provide:

  • individual statistical data;
  • statistical data which can be matched in a way that enables the identification of a specific statistical unit;
  • statistical information which aggregates data about less than three statistical units or about a population in which the relative share of the value of a surveyed parameter of a single unit exceeds 85 per cent of the total value of such parameter for all units in the population.

The individual data may be provided only if:

  • it is transferred to Eurostat where this is necessary for development and production of European statistical information;
  • it is provided to the National Statistical Institute by statistical authorities where this is necessary for development and production of official statistical information;
  • the subject to which such data relate has granted consent therefor.

Individual anonymous data is provided for the purposes of scientific research to higher schools or legal entities, whose main activity is scientific research, with a permission of the Chairperson of the National Statistical Institute.

According to the Law of statistics the receipt, processing, usage and storage of statistical data representing statistical secret is carried out in a procedure set out in a regulation endorsed by the President of the National Statistical Institute.

The Section 3 of the Rules for Dissemination of Statistical Products and Services endorsed by the President of the NSI regulate the protection of secrecy of individual data.

The Rules for Provision of Anonymised Individual Data for Scientific and Research Purposes endorsed by the President of the NSI regulate the relations in terms of provision of anonymised individual data by the NSI for scientific and research purposes and the order of their  receipt by the users.

Rules for Provision of Anonymised Individual Data for Scientific and Research Purposes

7.2. Confidentiality - data treatment

Data are treated in respect of national legislation: Individual data are not published in accordance with article 25 of the Law on Statistics. The publishing of individual data can be performed only in accordance with article 26 of the same law.

Law on statistics

Specific rules for treating the data set with regard to statistical confidentiality are applied according to the Rules for Provision of Anonymised Individual Data for Scientific and Research Purposes endorsed by the President of the NSI.

Rules for Provision of Anonymised Individual Data for Scientific and Research Purposes

In case of data anonymization the following requirements are applied:

  • Anonymized data are separate statistical records which have been amended according to the best existing practices in order to reduce the risk of direct or indirect identification of the statistical units to which they refer
  • Additional data processing means deletion of names, addresses, identification numbers and all of the characteristics that might lead to a risk of disclosure and misuse of individual records in the databases with individual data. Measures such as suppression of geographical details, age, place of birth, occupation, economic activity, type of ownership, etc. that can be taken in order to ensure that the identification of individuals and economic entities shall be impossible.
  • Anonymised individual data cannot be provided if it is in conflict with the provisions of art. 25 of the Statistics Act;
  • The individual records in the databases of the requested survey shall be processed by competent employees as all identifying individual attributes (name, address, publicly accessible identification number etc.) which directly or indirectly a given statistical unit can be identified shall be deleted from the data through.
  • In case of records in which some of the characteristics do not fulfilled these rules, the directorates responsible for the preparation of the data shall decide whether they should be completely deleted or to delete the data only in the cells of these characteristics or to take other appropriate solutions for protection of individual data.


8. Release policy Top

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 release of the Bulgarian HICP follow a preannounced official Release Calendar presenting the results of the statistical surveys carried out by the National Statistical Institute.

The Release Calendar is publicly accessible on NSI’s website.

8.2. Release calendar access

Release Calendar

 

8.3. Release policy - user access

On the release date, the press release is sent to the President of the Republic of Bulgaria, the parliament, the government and the media simultaneously. The data for consumer price indices are accessible to all users through the website of NSI and through “Relations with Users and e-Services” Department in NSI.


9. Frequency of dissemination Top

Monthly


10. Accessibility and clarity Top

Bulgarian HICP is disseminated monthly. HICP data is published in the following NSI’s publications in printed and/or electronic format:

Monthy, in electronic format:

  • press release (CPI; HICP) – on NSI’s website, theme: Statistical Data - Inflation and Consumer Price Indices;
  • predefined tables (CPI, HICP) – on NSI’s website, theme: Statistical Data - Inflation and Consumer Price Indices;
  • on-line database (CPI, HICP) – on NSI’s website, Information System INFOSTAT.

Quarterly, in electronic format:

  • Key indicators for Bulgaria – on NSI’s website, theme: Statistical Data – Key indicators;

Annualy, in electronic and/or printed format:

  • Statistical Yearbook – printed edition and electronic edition on CD-ROM;
  • Statistical Reference Book – printed edition and electronic edition on CD-ROM;
  • Bulgaria brochure – printed edition.

The HICP rates are disseminated with one decimal. The index levels are disseminated with two decimals.

The HICP metadata and methodology are available on NSI’s website: https://www.nsi.bg/en/content/harmonized-indices-consumer-prices-hicp

All publications are available in both Bulgarian and English.

10.1. Dissemination format - News release

The press release ‘Inflation and Consumer Price Indices’ is issued monthly and the HICP data is included together with CPI and Price Index of Small Basket (PISB) data. The press release is regularly published to a strict, pre-announced time table - in general from 12 to 16 days after the month in a question. The HICP data included in the press release cover the price indices (2015=100), monthly indices and rates of change, annual indices and indices for the current month compared to December of the previous year.

10.2. Dissemination format - Publications

HICP table data and press release are available on NSI’s website, theme Inflation and Consumer Price Indices: https://www.nsi.bg/en/content/6065/harmonized-indices-consumer-prices-hicp

HICP data are also published in the following NSI publications in printed and/or electronic format:

  • Regular publications:
    • Key indicators for Bulgaria – quarterly, electronic publication;
    • Statistical Yearbook – annual, printed edition and electronic edition on CD-ROM;
    • Statistical Reference Book – annual, printed edition and electronic edition on CD-ROM;
    • Bulgaria brochure – annual, printed edition and electronic edition on CD-ROM;
  • Ad-hoc publications:
    • Brochure Consumer Price Indices and Inflation Answers to the Most Frequently Asked Questions
10.3. Dissemination format - online database

HICP database

On-line database on NSI’s website, Information System INFOSTAT: https://infostat.nsi.bg/infostat/pages/external/login.jsf

10.4. Dissemination format - microdata access

In principle, there is no access to microdata. The microdata, as long as it is not confidential, could be provided to users on request without a breach of the confidentiality principle.

10.5. Dissemination format - other

See also Eurostat´s HICP website:

https://ec.europa.eu/eurostat/web/hicp/overview

10.6. Documentation on methodology

The HICP Methodological Manual provides the reference methodology for the production of HICP. (https://ec.europa.eu/eurostat/web/products-manuals-and-guidelines/-/KS-GQ-17-015)

10.6.1. Documentation on methodology - national specifics

The HICP metadata and methodology are available on NSI’s website: https://www.nsi.bg/en/content/harmonized-indices-consumer-prices-hicp

10.7. Quality management - documentation

The HICP Quality Reports is available on NSI’s internet site: https://www.nsi.bg/en/content/15959/harmonized-indices-consumer-prices-hicp


11. Quality management Top

The quality activities in in Bulgarian National Statistical System (NSS) are built on the fifteen principles of the European Statistics Code of Practice, covering the institutional environment, statistical processes and statistical outputs. The NSS Quality Assurance Framework includes methods and tools that aim to guarantee the compliance with the requirements to the statistical processes and products, and to ensure the required statistical information quality.

Documents:

1. Strategic and methodological documents

1.1. European Statistics Code of Practice

1.2. Quality Management Policy

1.3. Quality Management Programme

1.4. Guidelines on quality criteria in the NSS of Bulgaria

1.5. Guidelines for quality assessment in the NSI

1.6. Handbook on Internal Quality Audit in the NSI

2. Quality assessment

2.1. Peer review on the implementation of the European Statistics Code of Practice (2007)

2.2. Analysis of the Internal Quality Survey - "Quality of the NSI Statistical Products" (2008)

2.3. Analysis of the Interviewers Satisfaction Survey (2008)

2.4. Quality Self-Assessment of Statistical Information in the NSS of the Republic of Bulgaria (2010)

2.5. Analysis of the Results from Quality Self-Assessment of Statistical Processes in the National Statistical System of Bulgaria (2012)

3. Quality reports

3.1. Business statistics

11.1. Quality assurance

11.1.1. Quality management - Compliance Monitoring

Compliance Monitoring

11.1.2. Quality assurance - national specifics

The quality activities in Bulgarian National Statistical System (NSS) are built on the fifteen principles of the European Statistics Code of Practice (https://ec.europa.eu/eurostat/web/quality/european-statistics-code-of-practice), covering the institutional environment, statistical processes and statistical outputs. The NSS Quality Assurance Framework includes methods and tools that aim to guarantee the compliance with the requirements to the statistical processes and products, and to ensure the required statistical information quality.

One of the main tasks of Consumer Prices, Housing prices and PPP Department is to control all processes, related to the CPI/HICP production with respect to the quality of the index results. The following processes are covered by that task:

  • Basket composition specification (i.e. items, weights, revision of weights, replacements of items, inclusion of new items, deletion of others);
  • Sampling of outlets and items;
  • Price collection (including substitution of outlets and items);
  • Data processing (e.g. data entry, data editing);
  • Adjustments for quality changes;
  • Index computation (i.e. mathematical formulae);
  • Personnel training;
  • Tasks carried out by external contractors;
  • Monitoring of the implementation of HICP production.

 

Evaluation of the completeness and accuracy of the information and assurance of the compliance of the HICP sub-indices with comparability and quality requirements

  • Quality assurance of introduction of change. The specific tools employed for quality assurance of change their usage is as follows: pilot testing of new/modified methods and procedures; parallel implementation of current and new/modified methods and procedures for a certain period of time; training of affected personnel.
  • Quality assurance of the work of external contractors. The quality of contractors’ work is ensured by: collaboration only with contractors which satisfy certain criteria in terms of quality of services; insertion of specific quality targets in contracts; monitoring of contractors’ work during implementation.
  • Quality assurance of the work of the price collectors is ensured by: following predefined monthly price collection schedule; crosschecks from regional coordinators. These checks are important step in assurance of the quality of fieldwork. The final verification of results is done by staff on central level.
  • Quality assurance of the work of the staff in central office of NSI responsible for data validation at national level is ensured by following the predefined consecutive steps for verification of received regional data: check of missing prices, check of indices` biases, check of correctly filled characteristics, check for the correctly use of codes, discussion of  problematic issues, decision making.
  • The procedures for the consistency of the output results rely on data validation and on the review of indices before dissemination. The senior members of staff of the Consumer Prices, Housing prices and PPP Department review the indices before publication. The validation of the indices goes down to quite detailed item groups. Usually the meeting with experts responsible for validation takes place and the various topics concerning the monthly production round are discussed (reported price changes, imputation rates, cases of quality adjustment, treatment of missing prices, etc.).
  • The documentation of the CPI/HICP processes exists in the form of guidelines, instructions for particular tasks and software manuals both at national and at regional level, but it does not cover the whole chain of CPI/HICP production. The following particular steps of HICP production are covered by the documentation: weights construction; sampling of items and outlets; price collection; data entry; computation of the index.
11.2. Quality management - assessment

11.2.1. Compliance monitoring - last report and main results

Compliance Monitoring

11.2.2. Quality assessment - national specifics

The CPI/HICP Quality Reports following the ESS Standard for Quality Reports Structure (ESQRS) are produced and are update each year.

The HICP Quality Reports is available on NSI’s internet site: https://www.nsi.bg/en/content/15959/harmonized-indices-consumer-prices-hicp


12. Relevance Top
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 main national users could be classified as follows:

  • National state institutions: National Assembly of The Republic of Bulgaria, the Government, Bulgarian National Bank, national and state agencies. That group of users are considered as most important.
  • Other national users: municipal authorities, research communities, students, business communities, media, etc.
  • Internal users: other statistical divisions in the NSI.

HICP/CPI outcomes are mainly used as input to economic forecasting and analysis, for preparation of the convergence reports, for contract indexation, deflating other series, etc.

12.2. Relevance - User Satisfaction

NSI conducts an annual statistical survey "Users' satisfaction" which covers all statistical domains. It aims to assess user satisfaction in NSI data provision and to outline the recommendations for future development of statistical system according to the needs of the users.

Analysis of the last survey conducted in 2018 are available on the following link: User satisfaction

The National Statistical Council (NSC) is established in accordance with Art.14 of Law on Statistics, as a consultative body, attached to the President of the NSI. The main tasks of NSC are: give an opinion and recommendations on the Strategy for Development of the National Statistical System for each 5-year period; discuss the proposals of the Bodies of Statistics and give recommendations for including in the draft version of the National Statistical Programme particular statistical surveys specified in kind, coverage and acting persons; support the National Statistical System activities on implementation of the National Statistical Programme; create, in case of need, constant or temporary working groups to deal with particular statistical issues in compliance with its competencies; cooperate with the European Statistical Advisory Committee (ESAC) (according to the Art. 3, Para 4 from Decision No 234/2008/EC of the European Parliament and of the Council).

12.3. Completeness

No missing data. Bulgaria produces and delivers the full set of HICP indices and weights.


13. Accuracy Top
13.1. Accuracy - overall

Statistical data are with good accuracy. The accuracy of HICP is assured by strictly following Eurostat's methodological recommendations and regulations. The type of survey and the price collection methods ensure sufficient coverage and timeliness.

13.2. Sampling error

The use of non-probability sampling (purposive sampling) makes it difficult to assess the sample error. Therefore and due to the complexity of price index structures NSI does not produce estimates on sampling errors. Nevertheless the NSI aims to avoid possible bias due to sample misrepresentation by using a sample of consumer prices that is as large as possible by the given resource constraints. The NSI tries to optimise the allocation of resources by indicating the number of prices that should be observed in each geographic area and each item category, in order to minimize the variance of the all-items index.

13.3. Non-sampling error

For the HICP non-sampling errors are not quantified. The NSI tries to reduce non-sampling errors through continuous methodological improvements and survey process improvements, which can help us to avoid coding and typing errors.


14. Timeliness and punctuality Top
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. Coherence and comparability Top
15.1. Comparability - geographical

HICPs across Member States are comparable. Any differences at all levels of detail should only reflect differences in price changes or expenditure patterns.

To this end, definitions and classifications have been harmonised in a series of legal acts. The HICP is produced according to these minimum standards that may be applied with some flexibility as long as 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 from an index compiled following the minimum standards (Article 4 of Council and Parliament Regulation (EU) 2016/792).

15.2. Comparability - over time

HICP data are fully comparable 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. However back calculations under the newer standards were performed when appropriate basic data was available and historical series were revised. The main referencing have been from 1996=100 to 2005=100 (since January 2006) and from 2005=100 to 2015=100 (since January 2016).

In January 2005 there is a break in HICP series due to changes in methods. Since January 2005 the domestic concept have been implemented in construction of HICP weights. Until December 2004, domestic concept had not been fully implemented into Bulgarian HICP.

15.3. Coherence - cross domain

HICP differs from national CPI in terms of population coverage – the consumption of both non-residents and institutional household are covered in HICP, while in the national CPI it is out of the index coverage.

There are no difference between HICP and the national CPI in terms of the:

  • Methodology;
  • Territorial coverage
  • Product coverage;
  • Treatment of product groups.
15.4. Coherence - internal

The HICPs are internally coherent. Higher level aggregations are derived from detailed indices according to well-defined procedures.


16. Cost and Burden Top

Not available


17. Data revision Top
17.1. Data revision - policy

The HICP series, including back data, is revisable at any point in time under the terms set in Commission Regulation (EC) No 1921/2001 of 28 September 2001. The published HICP data may be revised for corrections, and new or improved information.

17.1.1. Data revision - policy - national specifics

In general, monthly Bulgarian HICP/CPI indices are not subject to revisions. They are final when first released. The only exception is the HICP/CPI for January that is calculated and is published as preliminary data with flag ‘p’. Each year January index is firstly released as a preliminary index with preliminary weights. The reason is that data from HBS used for construction of the weights at the lower levels of aggregation is not available for the whole previous year. The January index is firstly calculated with HBS data from October of year t-2 to September of year t-1. The final January index is released together with the February index when the HBS data is available for the whole previous year (from January to December). The final January index replaces the preliminary one and is published as final data with flag ‘r’. Index numbers for the rest of the months of the year are final when first released.

17.2. Data revision - practice

Bulgarian HICP has been revised once in past 10 years. Due to this revision the 2005 HICPs (1996=100), 1997-2006 HICPs (2005=100) and 2005-2006 HICP weights have been revised.

In 2007 the Bulgarian HICP data for 2005 and 2006 has been revised. The reason was that since January 2007 Bulgaria has started to apply domestic concept in construction of HICP weights. Until December 2006, domestic concept has not been fully implemented into Bulgarian HICP. For ensuring the comparable index series, the monthly HICPs have been revised for the period from January 2005 to December 2006. The main objective was to have ‘clear’ HICP index series with the new index reference period 2005=100. The revision has been implemented in close coordination between NSI and Eurostat.

The revision concerned the weighting structure of Bulgarian HICP:

- Until December 2006 HBS data was the main source for HICP weights. The weight reference period (WRP) was equal to year t-1: HICP in year t was calculated with weights for year t-1 and the weights were price up-date to December of the previous year.

- Since January 2007 the main source for HICP weights is the NA data. The WPR was equal to year t-3: HICP in year t was calculated with weights for year t-3.

The following procedures has been used in doing the revision exercise:

1. Monthly indices for year 2005 were calculated with new weights (2002 NA data).

2. The link was done in December 2004 and revised 2005 HICPs were re-based to the old WRP 1996=100.

3. Revised 2005 HICPs (1996=100) were used for calculation of the revised rebasing factor (2005/Dec96) for re-basing of the historical index series (1997-2005) to the new index reference period (IRP) 2005=100.

4. Historical index series (1997-2005) were re-based to the new IRP 2005=100.

5. Monthly indices for year 2006 were calculated with new weights (2003 NA data).

6. The link was done in December 2005 (using the revised December 2005) and revised 2006 HICPs were re-based to the new WRP 2005=100.

January 2007 was calculated with 2004 NA data. It was linked in December 2006 and re-based to 2005=100.

The effects of the revision on index levels and index rates were:

1. Historical index series 1997-2004: index levels were affected, but rates were not affected.

2. 2005 HICPs: both index levels and rates were affected.

3. 2006 HICPs: both index levels and rates were affected.

The revised HICPs was published as follows: revised 2005 HICPs (1996=100) with flag ‘r’; revised 2005 HICP weights with flag ‘r’; revised historical index series 1997-2005 (2005=100) with flag ‘r’, round to 2 decimals; revised 2006 HICPs (2005=100) with flag ‘r’ and revised 2006 HICP weights with flag ‘r’. NSI asked Eurostat about Eurostat’s agreement on revision. The revision has been agreed. The flag ‘b’ (for break in series) had been also used between December 2004 indices and January 2005 indices.

The main reason for the revision was introduction of the new method.


18. Statistical processing Top
18.1. Source data

18.1.1. Weights

HICP weights in year t are constructed using the preliminary NA data for year t-2 at the highest level of aggregation. HBS data for year t-1 is used for construction of the weights at the lower levels of aggregation, where no information is available from the NA. Additional data sources for year t-1/t-2 are used for construction of detailed weights at the lowest level of aggregation.
Weights applied to different aggregation levels are reviewed and updated annually, based on the NA and HBS results and other data sources.

18.1.1.1. Compilation at elementary aggregate level

Two additional levels are defined below sub-index level: 5-digit level (sub-classes) and 6-digit level (EAs).

The lowest level of aggregation where explicit weights are introduced is 6-digit level (EAs).

Data from household budget survey (HBS) and from additional sources is used for construction of the weights at 5- and 6-digit level of aggregation. There are no cases where the weights are adjusted.

The main sources used in HICP weights construction are NA (t-2) and HBS (t-1). The multiple sources are combined as follows:

1. The HFMCE, according to the domestic concept, preliminary data for year t-2 is received from NA department.

2. The NA data for year t-2 is restructured to HICP structure for year t according COICOP/HICP classification. That is done at all levels of aggregation where the information from NA is available. When NA data is not available the HBS data for year t-2 or data from additional sources for year t-2 is used. The result is the full set of weights at all levels (from EA level to highest levels): NA t-2.

3. The NA t-2 data is price updated to t-1 prices in order to be able to combine it with HBS data for year t-1. The price update is done at EA level, where the index for price update is available. The higher levels are calculated as a sum from price updated lower levels. The result is to have NA data at higher levels of aggregation that is ready to be combined with t-1 HBS data: NA t-2(t-1).

4. The NA t-2(t-1) data is further combined with the HBS data for year t-1 or data from additional sources for year t-1 is order to derive the weights at lower levels of aggregation where the NA data is not available.

5. Finally, the weights are price updated to December t-1 prices.

The annual frequency of update of weights is applied at the elementary aggregate level.

Bulgarian HICP uses national stratification and the EAs are defined at national level. No regional / outlet / product weights are used.

 

18.1.1.2. Compilation of sub-index weights.

The weights at sub-index level are derived from NA based on year t-2.

Weights are adjusted in cases where there is available more up-to-date information at detailed level. Comparisons are made with the previous NA data or HBS data to detect possible anomalies. Results are discussed with NA in order to improve the quality of weights.

18.1.1.3. Reference period higher levels

The reference period of the data used for the calculation of the weights of sub-indices (ECOICOP sub-classes and higher) is t-2.

18.1.1.4. Weights - plausibility checking

The review and update of weights at lower levels is done during the annual updating of the HICP weights. The constructed weights are analyzed and validated at all hierarchical levels of aggregation (from lowest EA level to general index). Plausibility checking activities include:

  • analysis of consistency with other available sources of information - administrative sources, other statistical surveys, market researches, etc.;
  • analysis of outlined trends (absolute and relative) in comparison with the previous year weights to detect possible anomalies;
  • checking of the internal consistency of the weights.

18.1.2. Prices

The Bulgarian CPI/HICP price data is based on the following multiple data sources:

  • Survey data;
  • Web scraped data.

18.1.2.1. Data Source - overview  

See the Annex 



Annexes:
HICP_Inventory_detail_2020_BG

18.1.2.2. Scanner data - general information

Not relevant. The Bulgarian CPI/HICP price data is based on the survey data and on web scraped data. The scanner data is not used as data source.

 

18.1.2.3. Bulk web scraping - general information

The main types of retailer for which the prices have been web scraped during 2020 was on-line shops of the respective retailers. The web scraped data is used for the following ECOICOP classes and groups:

07.1.1  Motor cars – the weight covered by web-scraped data is 71%

07.1.1.2           Second-hand motor cars – the weight covered by web-scraped data is 100%

08.2.0  Telephone and telefax equipment – the weight covered by web-scraped data is 86%

08.2.0.2           Mobile telephone equipment – the weight covered by web-scraped data is 86%

09.1.3  Information processing equipment – the weight covered by web-scraped data is 38%

09.1.3.1           Personal computers – the weight covered by web-scraped data is 45%

09.1.4  Recording media – the weight covered by web-scraped data is 46%

09.1.4.0           Pre-recorded recording media – the weight covered by web-scraped data is 100%

09.3.1  Games, toys and hobbies – the weight covered by web-scraped data is 1%

09.3.1.1           Games and hobbies – the weight covered by web-scraped data is 13%

09.5.1  Books – the weight covered by web-scraped data is 89%

09.5.1.1           Fiction books – the weight covered by web-scraped data is 99%

09.5.1.2           Educational text books – the weight covered by web-scraped data is 50%

The foreign web-sites are not web scraped.

The prices of the following products collected using the web scraping fully coincide to actual purchaser prices, i.e. are equal to the prices paid in physical outlets:

- mobile phones;

- tablets;

- pre-recorded recording media (CDs);

- electronic games (for PC and console);

- books.

The prices of the following products collected using the web scraping are used as a proxy for physical shop price collection (i.e. as a price estimate for prices paid in physical outlets):

- second-hand motor cars;

- desktop computers;

Web scrapped data is resampled annually according to research of new available data sources.

18.1.3. Sampling design and procedure

18.1.3.1. Sampling design: regions - general information

The HICP covers the entire area of the country. All regions of Bulgaria are covered in the sample of localities where the prices for HICP are collected. The sample of localities is representative for the entire territory, the stratification of the index being national. No regional weights are used. 27 regions out of 28 (NUTS 3) are included in the sample.

18.1.3.2. Sampling design: outlets - general information

The sample of outlets is drawn using non-probability sampling technics (‘purposive’/‘judgmental’ sampling) and is defined jointly by central office and by Regional Statistical Offices (RSOs). The number and the structure of the observation points are done in a way that can assure the optimum number of prices collected, which are sufficient to represent national price change for any of observed groups. The number of observation points is determined proportionally to the population in the selected district centres and to the volume of retail sales. The main principle is to have different number of price observations/outlets in each district centre according to the population and to the volume of retail sales. The district centres are stratified in three groups: (1) capital, (2) ‘big’ and (3) ‘small’ centres.

 

The following main categories of outlets are covered, including supermarkets, hypermarkets, general and specialized stores and market stalls (open-air markets):

- hypermarket / large supermarket

- small supermarket

- outdoor (open-air) market (stall, stand)

- indoor market, bazaar, mall (stall, stand)

- services’ outlet

- catering services’ outlet

- specialized chain of stores

- specialized small shop

- small retail store

- other

18.1.3.3. Sampling design: products - newly significant goods and services

NSI systematically seeks to identify newly significant goods and services. Both completely new products and products that have been available for some time on the market but consumed in relatively small amounts are covered in this exercise. Newly significant good and services are introduced at the end of each year (in December) during the annual revisions of consumer basket. The newly significant goods and services have been introduced into CPI/HICP by adjusting category weight or by re-assigning weight to the new product. The procedures for identification of newly significant goods and services are based on:

• Analyses of HBS data on the structure of household expenditures;

• Price collectors’ information;

• Research and consultations with suppliers;

• Market research’ information;

• PPP survey.

The significance level for new products and services are measured based on information from HBS data and on market research’ information, if it is available.

In 2020 the following new products have been included into CPI/HICP: wheat, energy drink, leatherette jacket, ¾ jeans, short jeans, wine corkscrew, shoe cleaning sponge, bicycle tyre, back cover case for mobile phone, audio in-ears headphones, gaming laptop, laptop’ diagnostics, flower pot, 3D cinema ticket, mascara, baby wet wipes.

18.2. Frequency of data collection

Price data is collected every month.

18.3. Data collection

18.3.1. Price collection surveys

Regional price collection

In Bulgaria, most of the prices are also observed in regional price collection. In each RSO there is a unit responsible for the CPI/HICP survey. Approximately 70 price collectors located in 27 district centres do the regional price collection. The main methods used for regional price collection are: personal visit and phone interview.

The RSO units are led by a CPI coordinators that are responsible for the organisation of fieldwork and for the collection of prices of some products. The CPI coordinators work under supervision and in close collaboration with the staff in central office. Although the connection between central office’s staff and price collectors is mainly done by CPI coordinators, direct contacts are also established when it is necessary.

Training of price collectors:

Two or three days meetings/seminars for price collectors are organised once a year. The main purposes of these meetings are twofold: (1) to get an overview and to acquaint price collectors with legal acts, basic concepts, definitions and requirements for the CPI/HICP and (2) to instruct price collectors on requirements posed for their fieldwork, data entering and validation. The meetings /seminars cover all aspects of data collection process as well as how the collected data contribute to the final product (CPI/HICP). The special attention is paid to the quality of the collected data.

At the end of each year during the annual CPI/HICP revision several letters with written instructions for the price collectors are sent to RSOs. The letters cover procedures for selecting the particular product in outlets, for doing replacements, for treatment of discounts, etc.

The price collectors learn a lot from the staff in central office on regular basic during monthly CPI/HICP data processing and validation at national level. The price experts inform price collectors about the mistakes made and consult them on different issues. They also assist the price collectors in the right decision-making and instruct them in the collection of the information on prices. The experts and price collectors communicate by telephone and email.

Training of price collectors at entry into service

At the first stage, new price collectors are trained by CPI coordinators in RSO. The main purposes of this first training are twofold: (1) to get an overview and to acquaint price collectors with legal acts, basic concepts, definitions and requirements for the CPI/HICP and (2) to instruct price collectors on requirements posed for their fieldwork, data entering and validation. The special attention is paid to practical aspects: how to choose and change outlets, description of items, forms/tools used for the price registration, what kind of the information should be filled in, how to deal with missing prices, quality changes, seasonal products, etc.

On-the-job training during the first month of the new price collectors on the field. It is provided by experienced price collector.

Cental price collection

Part of price collection is done centrally by the staff in central office of NSI. The prices of the following products are collected centrally:

  • electricity;
  • some of the medical services: consultations of the physicians in general practice with contract with National Health Insurance Fund (NHIF); consultations of the physicians in specialist practice with contract with NHIF,
  • some of the dental services: services of the dentists with contract with NHIF;
  • hospital services;
  • new and second-hand cars;
  • air transport services;
  • letter handling services and other post services;
  • mobile phones;
  • fix and mobile services and bundled telecommunication services;
  • desktop computers and tablets;
  • pre-recorded recording media;
  • electronic games (for PC and console);
  • books;
  • packaged holidays;
  • accommodation services in resorts;
  • insurance connected with the dwelling;
  • motor vehicle insurance;
  • passenger transport by train;
  • toll facilities
  • banking services;
  • administrative fees;
  • legal services.

The main methods used for central price collection are: visiting the internet web sites of the respective suppliers and web scraping.

 

 

18.3.2. Timing of price collection

Prices of the most of goods and services are collected each month and the price collection period is between 1st and 28th calendar day of the month (prices are not collected during the weekends and public holidays) according to predefined schedule and are even distributed through the month.

18.4. Data validation

Process for validating the basic data

The monthly checks against errors and mistakes in price information are done during the validation stage of CPI/HICP production. Data quality checks and validation work is distributed between central office and regional statistical offices, but most of work is carried out at the ‘Consumer prices, Housing prices and PPP Department in the central office of NSI.

The data validation process at regional offices can be divided into two stages:

  • The first one takes place during the entering of the collected prices into electronic devices or into the computer system. In case of using electronic devices all relevant information is recorded at the time of price collection and the software have a number of checking routines which flag up to the collector if a price entered exceeds a given percentage change from the previous month’s observed price. In such circumstances, the price collector is immediately forced either to correct the data or to accept it providing some explanation. The software creates a message that informs price collectors that the price is missing. In addition the various codes are used by price collectors during field work: codes that explain missing prices(A-Temporary not on the market, B-Due to the seasonal reasons, C-Permanently not on the market, D-Other reasons); codes for promotions and sales (PR-Promotion, SR-Seasonal sale, IR-End of promotion/sale, PPR-Continuous promotion, TC-Permanently low price) and codes that explain replacements (NP-New product offer, without outlet change, NO-New outlet, without product offer change, NN-New product offer in new outlet)
  • The second stage includes checking and validating by price collectors/coordinators in regional statistical offices and if necessary, prices are cross-checked in outlets.

The validation of the data in the central office is done after the first index calculation. Data quality checks fall into the following types of validation: 'relevant' index change validation (extreme and unusual price levels/changes); missing prices validation; outlets/products replacement validation; product specification change validation; etc.

 

Procedures for testing the correctness and plausibility of outcomes

The monthly checks against errors and mistakes in preliminary index results are done during the validation stage of CPI/HICP production. Data quality checks and validation is carried out at the Consumer prices, Housing prices and PPP Department in the central office of NSI.

The validation of the data is done after the first index calculation. Data quality checks fall into the following types of validation: 'relevant' index change validation (extreme and unusual price levels/changes); missing prices validation; outlets/products replacement validation; product specification change validation; etc. Finally, the indices are reviewed before dissemination. The senior members of staff of the Consumer prices, Housing prices and PPP Department reviews the indices before publication. The validation of the indices goes down to quite detailed item groups. Usually the meeting with experts responsible for validation takes place and the various topics concerning the monthly production round are discussed (reported price changes, imputation rates, cases of quality adjustment, treatment of missing prices, etc.).

18.4.1. Data validation - price data

Procedures to detect data entry errors

The detection of the data entry errors (including the missing price observations) are done during the validation stage of CPI/HICP production. Data quality checks and validation work is distributed between central office and regional statistical offices, but most of work is carried out at the central office of NSI.

The data validation process at regional offices can be divided into two stages:

  • The first one takes place during the entering of the collected prices into electronic devices or into the computer system. In case of using electronic devices all relevant information is recorded at the time of price collection and the software have a number of checking routines which flag up to the collector if a price entered exceeds a given percentage change from the previous month’s observed price. In such circumstances, the price collector is immediately forced either to correct the data or to accept it providing some explanation. The software creates a message that informs price collectors that the price is missing.
  • The second stage includes checking and validating by price collectors/coordinators in regional statistical offices and if necessary, prices are cross-checked in outlets.

The validation of the data in the central office is done after the first index calculation using various reports/lists generated by the software. Data quality checks fall into the following types of validation: 'relevant' index change validation (extreme and unusual price levels/changes); missing prices validation; outlets/products replacement validation; product specification change validation; etc.

 

Treatment of the detected errors

The detected errors are treated as follows: each case (problematic price) is considered individually, trying to obtain additional information for removal of the error and all necessary modifications are done only on the basis of relevant information. When it is considered that the individual price observation have to be rejected and new observation cannot be established, the rejected prices are treated as missing observations following the minimum standards regarding the treatment of missing observations, imputations and replacement procedures in the HICP. The rejections or adjustments of the reported prices are done centrally during the validation process in NSI. The rejection/adjustment of one price observation is done on account of information related to the individual observation concerned. During the validation process in central office, the responsible experts contact with price collectors in order to derive additional information for the individual observation concerned. In addition, if it is considered, the prices are cross cheeked in outlets or in Internet.

 

Monitoring of the consistency of the price information over time

The monitoring of the consistency of the price information over time is done during data validation using the various reports/lists generated by the software. Data quality checks fall into the following types of validation: 'relevant' index change validation (extreme and unusual changes, comparison is done with previous month and monitoring of the number of the consecutive months with no price change); missing prices validation (number of the consecutive months with missing prices); outlets/products replacement over time validation.

 

Monitoring the consistency of the price information across similar products in the same period

The monitoring of the consistency of the price information over time is done during data validation using the various reports/lists generated by the software. Data quality checks fall into the following types of validation: extreme and unusual price levels, comparison is done between prices of the one and same product in the same period.

 

Editing practices and possible adjustment of price observations

There is no automatic rejection of observed prices in our validation process. Each case (problematic price) is considered individually and all necessary modifications are done only on the basis of relevant information. When it is considered that the individual price observation have to be rejected and new observation cannot be established, the rejected prices are treated as missing observations following the minimum standards regarding the treatment of missing observations, imputations and replacement procedures in the HICP. The rejections or adjustments of the reported prices are done centrally during the validation process in NSI. The rejection/adjustment of one price observation is done on account of information related to the individual observation concerned. During the validation process in central office, the responsible experts contact with price collectors in order to derive additional information for the individual observation concerned. In addition, if it is considered, the prices are cross cheeked in outlets or in Internet.

18.5. Data compilation

18.5.1. Index formulae

Bulgarian HICP is a Laspeyres-type index.

For compilation of price indices for elementary aggregates, the ratio of geometric mean prices is used.

The following number of decimals are applied:

  • The number of decimals that are applied for price observation is 2 decimal places with exception of the some tariff prices (electricity, heat energy, etc.) that are collected with more than 2 decimal places.
  • The number of decimals that are applied for weights is 13 decimal places.
  • Index figures are compiled and transmitted as unrounded information. Rates of change are calculated from index information rounded to 2 decimal places and the result are rounded to 1 decimal place.
  • Index figures are published with 2 decimal places. Rates of change are published with 1 decimal place.

18.5.2. Aggregation method

Aggregation steps from bottom up:

  1. Calculation of geometric mean prices
  2. Calculation of the elementary aggregates’ indices as ration of geometric mean prices.
  3. Calculation of the higher level indices as weighted average of the low level indices with corresponding weights.

18.5.3. Chaining and linking method

Bulgarian HICP is chained Laspeyres-type index. The weights are updated annually. HICP in year t is calculated with weights t-2 price updated to t-1 prices (Wt-2(t-1)), with base prices from year t-1 and index reference period t-1. Each year, the link is done in December, using an index for December of year t-1 calculated with weights Wt-2(t-1), and with index and price reference year t-1. Finally, HICP is rebased to 2015=100.

18.5.4. Quality adjustment

The following implicit methods for quality adjustment in Bulgarian CPI/HICP are used:

  • Overlap method is applied when the prices of the old and replacement items are available in the same period;
  • Bridged overlap - when the price movement of the product with the same characteristics and the same producer from the EA or stratum is used as a bridge for the price changes of the replacement and replaced products;
  • Direct price comparison - quality is not changed and the replaced and replacement products are comparable. 

The following explicit methods for quality adjustment in Bulgarian CPI/HICP are used:

  • Package-Size Adjustment – when the value of a change in package size, as a proportion of the price, is assessed as the relative change in package size.
  • Single-Variable Adjustment – when the value of the quality change between a replaced and a replacement product offer, as a proportion of the price, is assessed as the relative change in some function of one particular characteristic of the product offers.
  • Option pricing - when the price of the options of the item are available.
  • Judgmental quality adjustment and Supported judgmental quality adjustment - when additional information is available and assessed by judgement of validator or specialist.

The combined QA methods are also used.

 

There are no automatic QA procedures for any product group. Instead, the choice of method depends on the specific replacement situation and selected replacement product-offer.

18.5.5. Seasonal items - general information

Minimum standards related to the seasonal regulation are applied to fruits, vegetables, clothing, footwear, package holidays, tyres, some of the products of heaters, of small electric household appliances and of motorized major tools and equipment and to some cleaning services.

The fixed-weight approach is used for determining of the weights for seasonal items i.e. during the whole year indices of seasonal products are calculated with fixed weights.

Estimated prices for seasonal products that is out-of-season are calculated by ASE (all-seasonal estimation) or by CSE (counter-seasonal estimation):

  • For seasonal fruit and vegetables – ASE is used;
  • For seasonal clothing and footwear products – CSE  is used and where it is not feasible ASE is applied;
  • For heaters and fans – ASE is used;
  • For motorized major tools and equipment – ASE is used
  • For types – CSE is used;
  • Cleaning services – ASE is used;
  • For package holidays – ASE is used.


Annexes:
HICP_Inventory_detail_2020_BG
18.6. Adjustment

Not applicable.


19. Comment Top

National link to COVID-19 information:

https://www.nsi.bg/en/content/18159/basic-page/covid-19


Related metadata Top


Annexes Top
HICP_Inventory_detail_2020_BG