Statistics Poland (GUS)

Trade and Services Department

Statistics Poland (GUS)
Trade and Services Department
Al. Niepodległości 208
PL - 00925 Warsaw
Poland

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.

European classification of individual consumption according to purpose (ECOICOP)

The HICP covers the final monetary consumption expenditure of the household sector.

The main statistical variables are price indices.

The basic unit of statistical observation are prices for consumer products.

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.

3.7.1. 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 whole country is covered by NA, HBS and consumer prices survey. There are also no regions excluded in the price collection procedure.

3.8.1. Start of time series

The HICP series started in January 1997.

3.8.2. Start of time series - national specifics

In Poland, the HICP was first compiled in 1999. The data for the period 1996-1998 is estimated. See the HICP database

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 statistics.

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 documentation, can be found in Eurostat’s website - HICP dedicated section, namely recommendations on specific topics, under the methodology page, and guidelines, under the quality page.

None.

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.

The Law on Public Statistics issued on 29 June 1995 with further amendments.

According to policy rules (see point 7.1).
Only aggregated results are published.

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 Protocol on impartial access to Eurostat data for users.

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.

A reference to Eurostat's website and the HICP Release schedule is made in the section of Statistics Poland website dedicated to HICP.

All users have equal access to HICP data which is available in Eurostat’s database. There is no national pre-access to the data. In addition HICP indices and rates of change for Poland (‘All-items’ main heading) are available on Statistics Poland website after its publication by Eurostat. When most up-to-date data is published in the table, the information of the new data availability appears in the News section of Statistics Poland website.

Monthly

The HICP data for Poland is published on Statistics Poland website after its publication by Eurostat. Forms of publications include: table with data, reference to HICP data in the CPI News Release. All the forms of publications are both in Polish and English. The data for Poland is published the same way as by Eurostat, i.e. with one decimal place.

The 'all-items' HICP data for Poland is published on the Statistics Poland website (table with data) after its publication by Eurostat. Reference to HICP data is also made in the CPI News Release.

The HICP totals is published, for example, in the 'Statistical Yearbook of the Republic of Poland'.

HICP database: Eurostat’s website, Statistics Poland website.

None.

None.

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 basic methodology for the Polish HICP is presented in the publication 'Statistical Yearbook of the Republic of Poland'.

Additional information on methodology can be obtained on request from Statistics Poland Trade and Services Department.

Compliance Monitoring Information notes available in the Eurostat's web page Quality - Harmonised Indices of Consumer Prices (HICP) - Eurostat (europa.eu).

Documentation on procedures applied for quality management is available on the Statistics Poland web page Bulletin of Public Information / Activity of Official Statistics / Quality in statistics.

The legal basis of the quality policy of the Polish official statistics is the internal Regulation of the President of Statistics Poland (No 35 of 28th December 2011) on measurement, evaluation and monitoring of statistical surveys quality.

The applied quality policy is based on the following International and European standards:

• Fundamental Principles of Official Statistics
• European Statistics Code of Practice
• Quality Assurance Framework QAF
• Regulation (EC) No 223/2009 of the European Parliament and of the Council of 11 March 2009 on European statistics (amended on May 2015)

For measurement and assessment of the quality of statistical surveys, the following tools are applied:

• standard quality reports,
• standard quality indicators,
• self-assessment checklist,
• audits/peer reviews.

11.1.1. Quality management - Compliance Monitoring

Compliance Monitoring

11.1.2. Quality assurance - national specifics

Controls on quality of the data

To counteract possible errors or mistakes, controls are implemented at different stages of the survey.

Price collectors are supervised and continuously controlled by the staff of the Regional Statistical Offices (RSOs). 

There is a special software for the automatic control of codes, sale units and price range. If the discrepancy between the last month’s price and the current month’s price exceeds an indicated range, the software requires further checks to be carried out and comments are sent to the central office. Any replacements have to be commented upon and explained. Then the necessary additional information from all the RSOs is gathered by the central office and the Price Statistics Centre of the Regional Statistical Office in Opole responsible for the prices control at the country level. 

The final control is applied in the central office, which also takes into consideration prices of comparable products recorded elsewhere and suspected data are explained by the RSOs.

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

Quality reports prepared by Statistics Poland are adapted to ESS standards, they are statements concerning the quality of data, containing the description of the basic components of quality: relevance, accuracy, timeliness and punctuality, accessibility and clarity, comparability and coherence, as well as the amount of survey costs and the burden on respondents, confidentiality, transparency and data security.
Analysis of the quality of each component includes: the description of the component, the measurement of quality, proposals to improve the quality of a given component. Furthermore, the summary report indicates the scope of  components, in which it is possible to improve the quality and reduce the cost of the survey and contains an analysis of linkages between the individual components:

• Timeliness and accuracy of data,
• Accuracy and usefulness of data,
• Usefulness and timeliness of data,
• Comparability and usefulness of the data,
• Temporal and spatial comparability

To measure the quality of the individual components, quality measures are used. Quality reports both in the extended and a simplified version are universal in nature and apply to both full and representational surveys, company surveys, as well as household surveys, surveys based on administrative sources, census surveys or  surveys based on different sources of information, as the system of national accounts.
When analysing the survey in the context of the quality aspects, very helpful are also the recommendations on the quality, provided by the European Commission within the thematic regulations concerning individual statistical surveys.

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

Government, self-government administration, Central Bank, researchers, businesses.

Not available.

All requested ECOICOP indices and weights down to the 5-digit level are produced.

The accuracy of HICP is generally considered to be high. Any unusual price movements are investigated at all stages of compilation from the regional price collectors to the central office.

Statistics Poland tries to reduce the sampling errors by using a sample of consumer prices that is as large as possible.

Statistics Poland tries to reduce non-sampling errors through continuous methodological improvements and survey process improvements such as computer assisted price collection, which can help avoiding coding and typing errors.

The full set of HICPs is published each month according to Eurostat’s Release calendar, usually between 15 and 18 days after the end of the reference month.

Each year, the January release is published at the end of February to allow for the annual update of the weights, both 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.

Since the March 1997, launch of the HICP release, the HICP for the country groups aggregates has always been published on the dates announced in Eurostat’s Release calendar.

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).

HICP data are 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.

Differences between the HICP and national CPI

The expenditure of institutional households and consumption expenditure of non-residents in the economic territory of the country is included in the HICP but excluded from the national CPI.

The consumption expenditure on games of chance is included in the national CPI but excluded from the HICP.

Due to the different coverage of consumption expenditure, the weights used for the HICP and CPI differ.

The main source of HICP weights are National Accounts while the system of weight for CPI is based on data from Household Budget Survey. Up to 2020 the National Accounts reference period for weights was the year t-2 (weights are price-updated to December t-1). For the HICP 2021, 2022 and 2023 weights reference period is t-1 (2020, 2021 and 2022, respectively). The household budget survey data for CPI derive from the year t-1.

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

Not available

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

The HICP series, including back data, is revisable at any point in time under the terms set in Commission Implementing Regulation (EU) 2020/1148 of 31 July 2020. The published HICP data may be revised for corrections, and new or improved information.

CPI is not revisable (the exception is data for January due to revision of weights).

The HICP compiled by Statistics Poland is subject to revision, when e.g. there are major changes in coverage or the methodology implemented. The data is also revised if mistakes are detected.

There were two cases of revision over the last 10 years:

• For January 2014: in connection with the introduction of the ECOICOP classification to the calculation of HICP indices since 2014 the weights and HICP indices for January 2014 were sent to Eurostat as preliminary data; after completing the software calculating the indicators according to the new classification, and after thorough examination and analysis, the revised data was again sent to Eurostat.
• In 2017 because of the need to exclude public insurance connected with health (ECOICOP subclass 12.5.3.1).

18.1.1. Weights

Weights are calculated using NA data (t-2) and are updated annually. Where necessary data obtained from NA is disaggregated into lower level based on HBS data. For the calculation of the index in a given year a weighting scheme is used covering 12 consecutive months from two years before, expressed in the prices from December of the previous year.

Due to the influence of the COVID-19 pandemic on the structure of household expenditures, the 2021, 2022 and 2023 weights were based on data representative for the year t-1 (2020, 2021 and 2022, respectively) – most recent 2019, 2020 and 2021 (respectively) national accounts data was adjusted based primarily on available NA and HBS data for the year 2020, 2021 and 2022 (respectively).

18.1.1.1. Compilation at elementary aggregate level

Weights are calculated using NA data (t-2) and are updated annually.  

18.1.1.2. Compilation of sub-index weights

In some cases within ECOICOP subclasses, there is an additional national 6-digit level. Where necessary data obtained from NA is disaggregated into lower level based on the results of the Household Budget Survey.

The calculations were based on the most recent version of 2021 expenditures, as available from the national accounts, including the ECOICOP breakdown. The next steps were applied to make them representative for the year 2022, based primarily on available NA and HBS data for 2022.

To make NA 2021 data representative for year t-1 further calculations at the lowest ECOICOP level were made based on the available HBS data for 2022 supported by short-term statistics. The methods were based on multiplying the 2021 value by an indicator of the change in HBS expenditure between 2022 and 2021. The changes between 2022 and 2021 were compared with retail sales data.

As the last quarter of 2022 was not available in the source data (HBS), the shares of consumption derived for the available quarters of 2022 were used as an approximation. On the basis of available sources, sub-index weights were verified to take into account the whole year (not only the expenditures of the most heavily affected segments but all segments of consumption).

18.1.1.3. Compilation of sub-index weights

For each level of the HICP index the same reference period is applied. For the calculation of the index in a given year a weighting scheme is used covering 12 consecutive months from the previous year, expressed in the prices from December of the previous year.

18.1.1.4. Weights – plausibility checking

Weights are updated annually using NA and HBS data. e.g. the direction of changes is compared.

18.1.1.5. Price updating

Weights for elementary groups are updated according to appropriate indexes, which are expressed in the prices of December of the previous year. Weights for the higher levels of aggregation are formed by summing the corresponding elementary groups.

All calculations of HICP 2023 weights were based on HFMCE for 2021 and 2022 and HBS (mainly) expenditure data for 2022. Price–updating was not applied (apart from the one mentioned below).
The weights obtained for each sub-index were multiplied by the ratio between the corresponding HICP sub-index for the average of 2022 and December 2022.
The price-updating was applied at ECOICOP6 (or EOCOICOP5 if relevant).

18.1.1.6. Compilation of total household final monetary consumption expenditure

As usually National Accounts data is used. However, as the data for the full year 2022 is not yet available, some estimates had to be made by NA.
The annual estimate of the HFCE was based on data for the first 3 quarters of 2022 (2022 Q1-Q3); 2022 Q4 data was estimated taking into account available branch statistics and business tendency survey.
As regards the components excluded from the HFCE to switch to HFMCE, generally speaking, some components are based on 2021 data and indexed by adequate indices to reflect the year 2022 (e.g.: Games of Chance are indexed with value index 2022/2021 of tax revenues from the gambling tax). Some components (such as administrative charges of private pension funds as well as FISIM) are based on NA quarterly data for the first 3 quarters of 2022 and the estimates for the Q4.

The 2022-Q4 HFCE data was estimated taking into account available branch statistics and business tendency survey. On the basis of NA quarterly data for the first 3 quarters of 2022 and the estimated Q4 the value of HFCE for the whole year 2022 was obtained. Transition from HFCE to HFMCE was made by estimating separately the value of the components necessary in transition.

18.1.2. Prices

Price data is based mainly on survey data sources. In addition, on transaction data obtained directly from data providers. Also web-scraping is being introduced.

18.1.2.1. Data Source - overview  

Price data is based mainly on survey data sources. In addition, on transaction data obtained directly from data providers. Also web-scraping is being introduced.

18.1.2.2. Scanner data - general information

During the covid pandemic months, scanner data was used as an additional source for some food categories. The approach is still used now. 
Scanner data is also used as an additional data source for some household articles (e.g. cleaning products) and articles for personal hygiene.

18.1.2.3. Web scraping - general information

Since 2023 web-scarping was introduced as an additional data source for some food categories as a replacement for some of the manual collection of prices from the Internet.

18.1.3. Sampling

18.1.3.1. Sampling design: locations for survey

The whole country is covered by NA, HBS and consumer prices survey.

In the price collection procedure there are no regions excluded. Prices are collected among 16 voivodeships. A voivodeship is the highest level of fundamental territorial division of the country (territorial self-government). For the purpose of the price survey, in each voivodeship there are price survey regions (their number depends on the size of the voivodeship). There are 207 price survey regions in total.

18.1.3.2. Sampling design: outlets

Price quotations are conducted in retail outlets, in catering establishments and in entities providing services that fall within the price survey region. The outlets involved in the survey sample correspond to the most common shopping venues and reflect the diversity of a distributive network within the price survey region. The prices of consumer goods and services are quoted in approximately 170 retail outlets per survey region.

18.1.3.3. Sampling design: newly significant goods and services

The verification of items is performed once a year, while the replacements (change of a particular quoted product with specified quality parameters and manufacturer in the region of price survey) are done when the need occurs.

Identification of the newly significant goods and services is based on proposals from regional statistical offices, detailed HBS sourced data, available transaction data, experts and users. While observing local markets, the price collectors gather information concerning changes in the assortment offered, sales structure, market sectors and significance.

New items are included in the price survey at the beginning of a new year. To achieve price dynamics in January in relation to the previous month, there is an additional quotation performed in December t-1. However, in the case when there is a necessity to change the product quoted so far at the retail outlet to another one, within the same description of the item, the changes occur on an ongoing basis. Completely new items are distinguished from the ones with the altered (updated) description concerning basic quality parameters

Price data is collected every month.

18.3.1. Price collection surveys

Survey data is collected mainly by price collectors. There are 207 price collectors on permanent basis. The price collectors also conduct other surveys not connected with prices, e.g. living conditions surveys and the LFS. In recent years, other methods of obtaining data have become more important. The share of items for which prices are collected centrally is increasing. Their share amounts to more than 20% of the sample.
The central (or quasi-central) collection of data related to price includes the following: uniform retail prices in the country, prices of selected goods and services purchased via the Internet, used cars, new cars (in addition to field collection), financial services provided by banks, electricity and gas.

Transaction data obtained directly from their owners is also gradually implemented: motor vehicle insurance, health insurance (in addition to field collection), insurance connected with the dwelling (in addition to field collection), travel insurance, other insurance (in addition to field collection), fuels for personal transport equipment. 

Since 2023 web-scarping was introduced as an additional data source for some food categories replacing part of the manual collection from the Internet.

Within the survey of uniform retail prices in the country, the categories observed are, for example: pharmaceuticals (with reimbursement); sanatorium services; transportation services; postal services; telecommunications services; radio and TV payments; newspapers; magazines; administrative fees; legal and accounting services.

Within the survey of retail prices of goods and services purchased via the Internet, prices of items which reflect the most popular product groups purchased from online shops are quoted. Items belong for example to the following groups: food and non-alcoholic beverages (since 2017); clothing; footwear; furniture for apartments or houses; bedclothes; basic household appliances; motor tools and equipment; pharmaceuticals; therapeutic devices and equipment; spare parts and accessories for private means of transport; telecommunications equipment; equipment for receiving, recording, and playing sound and sound and images; phonographic and cinematographic equipment; equipment for processing information; recorded storage devices; durable-use equipment for indoor recreation; games, toys, and collectable goods; sports and camping equipment for outdoor recreation; goods for household pets; photography services; books; package holidays; accommodation services; other personal hygiene devices, goods and products; watches and clocks; goods for children.

When price collection failed because of coronavirus pandemic restrictions that did not allow price collectors to visit sampled outlets or because outlets have been closed down, the missing prices were replaced using the outlets’ websites and telephone and email enquiries.

18.3.2. Timing of price collection

The price recording period lasts from the 5th till the 22nd day of the reporting month (since 2011). Survey on fresh fruit and vegetables prices is conducted twice a month, between 5-13 and 14-22 day of a month.
Due to coronavirus crisis for some months the quotation period was modified to maintain the similar number of price quotations (to an extent possible).

Verification of prices: collectors verify all price changes and are required to provide explanation for unusual movements. Special software is used for this purpose. Statisticians analyse data to ensure that price movements are consistent with external information, such as market observation results, trade statistics and producer price statistics.

Data validation: checks are made at all stages of index compilation – starting from price collectors up to the central office staff.

Price changes are subject to in-depth analysis, both at the regional and national level. In the case of a different trend (e.g. increased demand but a drop of prices in the case of seasonal articles in high season, and/or the presence of the opposite trend in certain region of price survey in comparison to other regions), such situation is explained and adjusted if justified. Similar explanations are applied to extreme price level values – analysis is focused primarily on quotations of the new or seasonal items in the first month of the new season.

18.4.1. Data validation - price data

Quotations of individual items are thoroughly analysed at various stages of index calculation. Price collectors use mobile devices with a special program that has been developed to compare the price of the surveyed month with the price from the previous month. If the calculated price index exceeds the specified range, software requires a detailed check, carried out by the price collectors in the field. In case when it is impossible to quote a particular item, the program enforces entering a special code to indicate the absence of quotations. The need to use the code in the absence of quotations indicates that the pollster did not forget about the quotation, and the particular product or service is simply not available in a given area. In the case where it is a temporary lack of quotations, the missing price is estimated at a later stage. If the recorded price is correct, i. e. it applies to the item comparable in quality to the previous month, the price collector selects the special code explaining the decrease or increase in the quoted prices. However, if the item is different in terms of quality than the one quoted in the previous month, this situation is also indicated in the program by the price collector, in order to, at a later stage of the analysis, make an adjustment for a change in quality. Then checks are carried out of the completeness and adequacy of the quoted items at the level of voivodeships. The missing information and outliers prices are explained. The next step is to analyse the quoted prices across the country. It is pursued by one of the regional statistical offices specializing in price surveys. At this stage, attention is also paid to the completeness, quality and accuracy of the quoted prices, missing prices and price outliers unconfirmed at an earlier stage.
The final check is carried out at the central office during the calculation of the index. At this stage, the prices of comparable products quoted in other regions are taken into account. Suspicious/uncertain data is examined again with the regional statistical offices.

In addition to the expert analysis of the developed indexes, the Department uses specially developed software in order to validate the calculated data.

18.5.1. Elementary price index formulae

Polish HICP is a Laspeyres-type index. Pursuant to legislation Jevons index, i.e. geometric average of the price relative of the month analysed and the previous one, is applied in order to calculate monthly price indices (the previous month = 100) for basic aggregates. Monthly indices with the base of December of the previous year for basic aggregates are calculated with the use of chain linking method with the application of indices with the previous month base. While preparing weights and indices data for publishing purposes, the highest possible accuracy is applied.

18.5.2. Aggregation of different data sources

The data basis and first stages of the calculations are the same for CPI and HICP.

Prices

• the prices are collected every month by price collectors in 207 survey regions, as well as centrally

Index from prices

• in the case of the data collected by price collectors, the next step is to calculate an index for a particular item for each of the survey regions, i.e. unweighted price to price comparison (current month to previous month); next, the national index for a particular item is calculated, i.e. a geometric average of all indices from all survey regions,
• in the case of central collection, an index for a particular item is calculated, i.e. unweighted price to price comparison (current month to previous month);

Aggregation of items into elementary aggregates (m/m-1 indices)

• the obtained price-to-price indices are then aggregated into the lowest levels of classification (ECOICOP 5-digit levels or lower 6-digit level); this is done with the use of the Jevons index (unweighted geometric mean of the price relatives – obtained in the previous stage, i.e. current month to previous month); we obtain the monthly price indices (the previous month = 100) for elementary aggregates

For the purpose of the HICP the next steps are:

• m/Dec t-1 indices for elementary aggregates

Monthly indices with the base of December of the previous year for elementary aggregates are calculated with the use of chain linking method with the use of m/m-1 indices  

• m/Dec t-1 indices for higher levels of aggregation

The elementary indices (m/Dec t-1) are then aggregated upwards (ECOICOP classification) using fixed annual weights according to Laspeyres formula

• m/2015=100 for elementary and higher level categories

Monthly indices of the given year (2015 = 100) are calculated with the use of the chain linking method and the monthly indices (December of the previous year = 100).

18.5.3. Chaining, linking and splicing methods

Chain linking method is applied at two stages of index calculation. To calculate monthly indices for elementary groups with the base of December of the previous year with the use of monthly indices (the previous month = 100) and to calculate one-based indices (2015 = 100) using monthly indices (December of the previous year = 100).

18.5.4. Quality adjustment – Detailed information

Replacement of an item takes place in the situation when the product being so far an item will not be sold any more or it will become less common/popular. The following corrections of quality are used:

• direct comparison – when a new product is regarded to be equivalent to the previous one as far as the quality is concerned, which means that it comes from the same manufacturer, it has the same qualitative parameters significant for the purchaser, it has the same sales unit or there is a minor difference related to this matter, it has packaging of the same type, it is of the same kind, the differences are insignificant for the purchaser and may concern characteristics connected to consumer’s taste and preferences,
• correction related to changes in packaging sizes – a method used in the case of changing the product weight by the manufacturer, the size of the packaging being the only significant change of quality,
• overlap – permissible in the case of change of outlets, the old and the new one are observed at the same time (so called double-track quotation is performed),
• bridge overlap – the only possibility to estimate the quality change is to acknowledge that the price change of the substitute item in a particular survey region is equivalent to the average price change of the items quoted in the other or selected (e.g. these where the quotations are performed in the retail outlets of the same type) price survey regions,
• option costs – a method used when a new product’s quality is better in comparison with the previously observed one, i.e. it was enriched with an additional characteristic, and information on the price of this supplement is available and possible to estimate,
• expert method – used mainly during quotations of uniform prices in the country or goods purchased via the Internet.

Example of applying quality adjustment methods:

• correction related to changes in packaging sizes – e.g. food, chemicals,

Indirect methods of quality correction:

• overlap – permissible in the case of change of quotation point,
• bridge overlap – for a variety of products,
• direct comparison – e.g. clothes and footwear, books, computer games (rapidly changing market), recorded storage devices.

B-type methods are most commonly applied.

Estimation of the impact of quality adjustments on national CPI/HICP has been made for ECOICOP 03 (clothing and footwear) - the index was calculated without QA (mainly bridge overlap). The adjustments significantly lowered the value of the index. As a result the product descriptions has been widened to allow mainly for direct comparison of products.

The pandemic redefines some concepts in the areas of quality changes, including, for example, a small/large quality changes assessment, what is a new product. There is a significant impact of technological progress, a change in the manner of providing many categories of services, sales channels etc. In 2022 downsizing process intensified.

18.5.5. Seasonal items

Following the requirements specified in Commission Regulation No 330/2009 (repealed and replaced by Commission Implementing Regulation (EU) 1148/2020), since 2011 Statistics Poland have modified methods of including seasonal products. Initially, the changes concerned only groups mentioned in the regulation (‘Fish’, ‘Fruit’, ‘Vegetables’, ’Clothes’ and ‘Footwear’), however, over the years new policy was applied to other seasonal items.

Not applicable.

Due to coronavirus pandemic since around the middle of March 2020 (closed shops, lack of provision of some services, inability to collect prices in the field), there was a different approach to data from March 2020.

For information on the compilation of the HICP during the COVID-19 crisis please see Eurostat HICP metadata.