Methodology - monthly sales indices in trade and wholesale trade


(covering section G and CZ-NACE 46) in the CZ-NACE classification (Czech version of the NACE Rev. 2 classification)

I Basic definition of  the measured economic activities

The scope of economic activities measured within short-term statistics results from current regulations of Eurostat. With regards to the requirements, the business-cycle statistics provides information on the development of sales in enterprises the principal (prevailing) activity of which is in trade (CZ-NACE section G, “Wholesale and retail trade; repair of motor vehicles and motorcycles”) and wholesale trade (CZ-NACE 46, “Wholesale trade, except of motor vehicles and motorcycles”).

II Data source

Administrative data – value added tax (VAT) tax returns are the data source. Based on administrative data, total sales from sale of goods, services, and goods for resale excluding VAT in the relevant month are modelled. Therefore, there is no burden on respondents.

III Population, methods of imputations and estimation

1 Population

The population consists of units that are considered to be active, are classified to the aforementioned CZ-NACE economic activity, and do their business in order to make profit. Units are selected from the Statistical Business Register based on their principal (prevailing) activity.

The sample does not include entities belonging to the non-business sphere (organisational units of the state, semi-budgetary organisations partially funded from the state budget or local budgets, and non-profit organisations).

As for important units, data of which have a significant impact on results for individual industries (economic activities), data are measured for kind-of-activity units, i.e. in the breakdown by economic activity of the given unit.

2 Methods of imputations and estimation

The sample is divided into strata based on 4-digit aggregate of the CZ-NACE and size group according to the number of insured persons. The monthly sales for a monthly VAT payer are calculated from the VAT tax return in the relevant month. The monthly sales for quarterly VAT payers and non-payers are added according to monthly VAT payers in the stratum. The sales of individual enterprises are added up in 3-digit CZ-NACE aggregations.

3 Description of sales indices calculation

The sales index shows how sales changed (increased or decreased) in the reference period when compared to the comparison basis. Depending on the index type, the comparison basis is either the corresponding period of the previous year (year-on-year index) or the average period of the base year (fixed-base index).
The sales index is used for short-term development analyses and possible predictions of the future development in individual CZ-NACE economic activities.

Calculation of indices:
For each 3-digit aggregate of the CZ-NACE, the y-o-y sales indices at current prices are calculated for individual months. For these CZ-NACE groups, y-o-y price deflators are used for individual months of the current year; for the base year, price deflators are related to individual months and to the year’s average. Absolute values of monthly sales at current prices for 3-digit CZ-NACE aggregates are converted into the price level of the base year using the method of chain-linked deflators. From a set of fixed-base indices at constant and current prices on the basic level of 3-digit NACE in the whole time series, year-on-year indices and absolute values of sales for a higher aggregation CZ-NACE 46 are then calculated. For deflation of sales to constant prices, price deflators excluding VAT related to the base year 2021 were used.

The aggregation for the CZ-NACE section G is calculated in a similar way and besides CZ-NACE 46 it also includes data for CZ-NACE 45 and 47 from the “SP 1-12” monthly survey.

4 Change of the base period in 2024

In 2024, the base period for short-term statistics changed, which is a standard step made usually every five years and co-ordinated within the European Statistical System.

  • The base period for fixed-base indices changed from the average of the year 2015 to the average of the year 2021.
  • New weighting schemes are used that are derived from results of the structural business statistics for the year 2021.
  • In compliance with the Eurostat manual on short-term statistics, new weights were used for recalculation of data back to the year 2020, which entailed a revision of data for 2020–2023.
  • Data for the years 2000–2018 were connected with updated results by means of conversion bridges by the annual overlap method. It is characteristic for this method that 2019/2018 year-on-year indices for the entire year cumulation remain after the connection the same as at the original data and the course of the series for the years 2000–2018 does not change either, i.e. after the connection the year-on-year indices remain unchanged. However, a consequence of the change is that historical series before the year 2019 lose their additivity; it means that they cannot be aggregated by means of the up-to-date weighting scheme.

IV Overview of basic published indicators

Year-on-year indices in constant prices

Year-on-year indices in current prices

Base indices in constant prices

Base indices in current prices

The indicators are published in the form of unadjusted data, calendar effects adjusted data and seasonally adjusted data (including adjustment for calendar effects). Data are published monthly, quarterly and annually.

V Retrospective corrections, revisions, estimate refinement procedure

In accordance with the revision policy of the CZSO, standard revisions are made in the “ADMDPHSP” task with the aim to enhance quality of a previously published piece of data by inclusion of updated administrative data. Along with processing of data for each month (except for January), a revision of data for the previous month is made; for example, concurrently with processing of data for February, a revision of data for January is made. Final data are published following the processing of all months of the reference year, in March of the following year at the latest.

VI Comparability

1 Comparability over time

The data come from the same data source and there were no methodological changes in the survey, so they are completely comparable over time.

2 Comparability with other surveys

Results of monthly surveys may differ from results published from annual surveys. Monthly data are required (in order to comply with a publication outputs release calendar) within deadlines when tax returns are not available for all enterprises for the reference period and therefore they are replaced by an informed guess. Moreover, during the final processing, which is made two years after the end of the reference year, data from annual surveys are modified according to the latest administrative data available.

3 International comparability

In the European Union, the short-term statistics domain is governed by the valid Regulation (EU) 2019/2152 of the European Parliament and of the Council of 27 November 2019 on European business statistics, repealing 10 legal acts in the field of business statistics. Under this Regulation, Member States of the EU are obliged to provide information on the development of turnover in trade (at current and constant prices) on a monthly basis.

VII Seasonal adjustment

The size of sales during a year in some industries (CZ-NACE economic activities) strongly depends on the season. In order to find out long-term trends but also to be able to compare month-on-month or quarter-on-quarter development, the CZSO
uses seasonally adjusted data, in which the part of sales caused by a different number of working days in a month and by seasonal fluctuation is separated from the original “rough” series, using a mathematical model. After the seasonal adjustment is made, not only y-o-y but also m-o-m (q-o-q) development can be compared. Along with publication of adjusted time series, data have been recalculated backwards as of January 2021. Together with a revision for a year, an adjustment model is changed and therefore the whole time series is recalculated.

The TRAMO/SEATS method also recommended by Eurostat is used for seasonal adjustment. The CZSO uses the NbDemetra programme, 2.2.2 version. So-called indirect method is applied – seasonal adjustment takes place on the lowest source aggregates of the sales index and an adjustment of higher aggregations is a weighted average of adjusted source data.

Data publishing

Results are published:

1) In time series in the Public database of the CZSO
2) They are regularly sent to
Eurostat databases.

3) In other documents at

IX Additional methodological information and external links

Weights of CZ-NACE economic activities in total sales in trade in the base year (2021)

Eurostat: Data series metadata: Turnover in trade

EU short-term statistics legislation

Methodology of short-term business statistics (Interpretation and guidelines)

Contact: Jana Gotvaldová, phone number: (+420) 274 052 691, e-mail: