|Adjustments||Not Seasonally Adjusted|
CPI is a Laspeyres type of index which measures changes in the prices of goods and services bought for consumption purposes by the households in Poland.
Indices are disseminated with the year 1998 as a weight reference period. In addition, the indices are also published for the following reference periods: December of previous year; previous month; and corresponding period of previous year.
Harmonized Indices of Consumer Prices (HICP) are computed according to uniform methodology of European Union by member states.
Classification system: Before 1999 - national classification of expenditures applied for Household Budget Survey. From 1999 onwards - Classification of Individual Consumption by Purpose (COICOP).
Scope of the data
Population coverage: All private households residing permanently in Poland, excluding institutional households and foreign households. Geographic coverage: Entire area of the country. Prices are collected in 209 price survey regions. The region may be a small town or a part of a large city (e.g. a district). A purposive selection of regions was based on the size of population, density of a shop network and price behavior of goods and services.
Item coverage: All goods and services bought within the domestic territory by the reference population for the purposes of consumption. Expenditures for cash gifts, life insurance, imputed rents, illegal activities are excluded. There are about 1,800 representative items chosen for CPI in 2006.
Exceptions to coverage
Population coverage: All private households residing permanently in Poland, excluding institutional households and foreign households.
Item coverage: All goods and services bought within the domestic territory by the reference population for the purposes of consumption. Expenditures for cash gifts, life insurance, imputed rents, illegal activities are excluded. There are about 1,800 representatives items chosen for CPI in 2006.
Types of prices: Prices reflect those that consumer pay on the day of the survey, taxes e.g. value added tax and excise tax.
Source data collection programs
Item selection: Purposive. Selected items should represent price movement of the commodity or service group and should be available for reasonable length of time. Number of representative goods and services per group depends on its weight and variability of price movement in the group. A list of representative items is updated annually. Selection of products/varieties is also purposive. Within item specification, price collectors, in cooperation with shop assistants, select products with significant market share
Outlet selection: Price collection is done in various types of outlets, such as those of middle size and common type, specialized in certain assortments, departments stores, supermarkets, big trade centers, and also pharmacies, patrol station, kiosks and permanent open-air market-places. Prices are not collected in temporary sales points.
Sample sizes: On average, there are about 292 thousand prices collected each month in 209 price survey regions.
Price collection methods: Price collectors are equipped with electronic devices called “tablets” to register prices in most retail outlets. Some prices (i.e., centrally determined) are collected by phone or using price lists sent by mail to the CSO. Internet is included as one of source of information on prices.
Item/variety specification: CSO supplies general specifications for most of the items to price collectors (e.g., women's jacket), who record detailed descriptions covering characteristics, such as brand, size, fabric/material, etc. However, fairly narrow descriptions for some items are also applied.
Source data timeliness
Timing of price observation: Collection is spread over the first 25 days of the month. Prices of goods and services are collected once a month. Fresh fruit and vegetables are priced three times a month.
Sources of weights: The CPI weights are derived from average annual expenditures primarily taken from the monthly Household Budget Survey based on a sample of approximately 35,000 (in 2005) households per year (using the method of monthly rotation with a quarterly cycle). Some adjustments for expenditures on alcoholic beverages, tobacco and catering are made using retail trade data and national accounts estimates.
Time period of current weights: Previous calendar year.
Frequency of weight updates: Annually.
Source data statistical techniques
Sources of weights: The CPI weights are derived from average annual expenditures primarily taken from the monthly Household Budget Survey based on a sample of approximately 35,000 (in 2005) households per year (using the method of monthly rotation with a quarterly cycle). Some adjustments for expenditures on alcoholic beverages, tobacco and catering are made using retail trade data and national accounts estimates..
Computation of lowest level indices: Individual relatives are first calculated for each price quotation in each survey area using the current month price and the reference period price. The national indices of each item and of elementary group are calculated using a geometric mean. Aggregation Laspeyres formula is applied for calculating price indices to higher levels of aggregation using weights from previous year.
Alignment of expenditure and base period: Weights are updated annually. The reference period for current weights is the year 2005.
Linking reweighted index to historical index: Historical series are constructed using a chain method. Due to the introduction of the COICOP classification in 1999, historical series are available only for the total CPI and for some narrow commodity and service groups.
Reference period: Previous year = 100. Indices are also presented with various reference periods (e.g. previous period, corresponding period of previous year, 1998 and 1995).
Treatment of missing prices: When a price observation is temporarily unavailable in a given month, its price is imputed. If permanently unavailable, a replacement is selected (group or class imputation). Price collector is asked to find another item meeting the specification. On average, there are about 1% of missing observations per month.
Adjustments for quality differences: Quality parameters of products surveyed are carefully observed to ensure their comparability. Each change in their descriptions is considered. In case of quality change, overlap or bridged overlap methods are mainly applied. If it is assessed not to be any substantial quality change then the price change is recorded as affecting the index.1:1. If there is a substantial quality change then the price change is assumed to be equal to quality change; or the new product prices is estimated, based on price dynamics of similar products found within the group in the region or the country. When no precise information is available to make a quality assessment, it is permissible adjustment to be made of 50% of the price difference. Hedonic methods are studied and some research is carried out.
Introducing new items: The list of representative items is updated annually based on information gathered by price collectors during the year. Usually, the RSOs are asked in August to send to the CSO their suggestions for changes. If their justifications for introducing new products on the list (or, conversely, deleting existing ones) are convincing and there are more such cases in the country, the proposal is considered at the annual meeting of CSO and RSO staff. New candidate products must represent a significant (and increasing) share in the turnover for the relevant group. Although it is recommended that the RSOs should keep the list of chosen products stable, replacements are necessary during the surveyed year if a new product appears on the market with a significant share of turnover.
Seasonal items: The variable weight system is used for calculating the index for seasonal groups of fruit and vegetables. The share of the “fruit” and “vegetables” groups in the weighting system for the reference period is fixed, while the internal structure of both groups varies depending on the seasonal months.
The basis of calculation of HICP for Poland is:
The grouping of consumer goods and services has been based on the Classification of Individual Consumption by Purpose worked out for the needs of HICP (COICOP/HICP).
Harmonized Indices of Consumer Prices is calculated in line with the Laspeyres’s formula.
In accordance with inflation criterion included in the Maastricht Treaty, HICP is a base for the stabilization price assessment. In Poland this index has been computed since 1997.
The final monthly data are published in the "Statistical Bulletin" and the final annual data are presented in "Statistical Yearbook". The only preliminary data are published for January. They are revised in the following month when first released and become final.
In accordance with the EU regulations, the retrospective data in the scope of HICP may undergo a change as a result of verification connected with the methodology modification.
HICP data from January 1996 to December 1998 is estimated by the source.