Volume index of industrial output: documentation of statistics

The volume index of industrial output describes the change in the monthly volume of industrial output at fixed prices. The purpose of the statistics is to provide fast and reliable information on the cyclical development in manufacturing at a detailed industry level.

The population comprises all industrial establishments and enterprises. Industries using turnover as their source data include all enterprises. Statistics Finland's own data collection for the volume index of industrial output is based on a sample made of industries, which includes enterprises of industries with the biggest value added.

The indices of the most detailed industry level (3-digit level) of the volume index of industrial output are calculated by means of separate strata. Stratum 1 includes establishments of enterprises with more than 150 employees. Stratum 2 comprises enterprises with over 50 but fewer than 150 employees. Stratum 3 comprises enterprises with fewer than 50 employees. For enterprises with fewer than 50 employees, indices calculated from the Tax Administration's self-assessed taxation data are used in stratum 3 instead of own data collection.

The statistical unit of the volume index of industrial output is a kind-of-activity unit.

The data of the volume index of industrial output are published as index point figures. Change percentages are also calculated based on the indices.

The base year of the time series is 2021 (2021=100).

The reference period for the volume index of industrial output is month. The statistics are published at a lag of 40 days from the end of the statistical reference month.

The volume index of industrial output is published on the level of the whole country.
However, the volume index of industrial output also includes activities performed outside the borders of Finland. The biggest enterprises are asked monthly in the sales inquiry about sales of goods and services from abroad to abroad. The data may include merchanting if it is reported in the financial statement of an enterprise operating in Finland. The data of the sales inquiry do not fully cover the definition of global production in the national accounts. The quality of turnover has been examined as concerns the biggest globally operating enterprises but there is no fully clear picture of how well it covers global production.

The volume index of industrial output comprises sections B Mining and quarrying, C Manufacturing, D Electricity, gas steam and air conditioning supply in the Standard Industrial Classification 2008. Apart from a few exceptions, the sub-series of the main groups are also published at the 2-digit level of the standard industrial classification.

The monthly data of the volume index of industrial output are available on the web pages starting from 1995.

The data of the statistics are published monthly on Statistics Finland's website.

The data of the volume index of industrial output become revised in later releases. The main reasons for revisions to the data are replacing estimates concerning missing source data at the time of publication with actual source data, other revisions or corrections to the data retrospectively and updating of the weight structure. In addition, seasonally adjusted series and trend series may change even if no changes took place in the original series. The models used in seasonal adjustment are updated once a year, when revisions can be larger than usual.
The population comprises all manufacturing establishments and enterprises. All enterprises are included in industries using turnover. Statistics Finland's own data collection for the volume index of industrial output is based on a sample made of industries, which includes enterprises of industries with the biggest value added.

The data of the volume index of industrial output are published at a lag of 40 days.

There is no delay in releasing data on the volume index of industrial output. The data are published on the days indicated in the release calendar.
 

The data of the volume index of industrial output become revised in later releases. The main reasons for revisions to the data are replacing estimates concerning missing source data at the time of publication with actual source data, other revisions or corrections to the data retrospectively and updating of the weight structure. In addition, seasonally adjusted series and trend series may change even if no changes took place in the original series. The models used in seasonal adjustment are updated once a year, when revisions can be larger than usual. Data revisions in main industries between different releases are presented in a table on the home page of the statistics:

 

The indices of the most detailed industry level (3-digit level) of the volume index of industrial output are calculated by means of separate strata. Stratum 1 includes establishments of enterprises with more than 150 employees. Stratum 2 comprises enterprises with over 50 but fewer than 150 employees. Stratum 3 comprises enterprises with fewer than 50 employees. For enterprises with fewer than 50 employees, indices calculated from the Tax Administration's self-assessed taxation data are used in stratum 3 instead of own data collection.

In terms of turnover data, the data contain under-coverage. The monthly data do not include small enterprises but they are supplemented with the acquisition of quarterly and annual data.

The non-response rate of the volume index of industrial output was 4.6 per cent in 2023.

Methodological time series modelling is used in the volume index of industrial output for part of industries when calculating indices for the latest month. In some of these industries, the latest data may, however, become substantially revised in later releases.
In addition, missing data for the latest months are imputed in the calculation. These may cause error if the imputations differ much from the actual observation later on.

European definitions according to the STS Regulation are used in the production of the statistics, so the data of the statistics are internationally comparable and cover the whole of Finland.

The monthly volume index of industrial output has been produced starting from 1950. Efforts have been made to make the data as temporally comparable as possible. However, changes have taken place over time in the calculation method of the statistics and the source data used, so the data cannot be considered fully comparable over time. In connection with the latest revision, some of the series have a break in the time series at the turn of 2016 and 2017 as the source data change. Industries produced on the basis of turnover indices describe production more extensively, also as concerns factoryless production and goods sent abroad for processing. The industries on turnover produced from 2017 onwards are listed in the methodological description of the statistics.

Business statistics produced by Statistics Finland can be divided into structural statistics and business trend statistics. The differences in the statistics are caused by their length of the description period, publication delay and the extent of the data content so that the description period and release delay of business trend statistics are shorter and their data content more limited than in the structural statistics. Structural business statistics include structural business and financial statement statistics that describe the structure and activities of enterprises on the annual level. Business trend statistics include monthly trend indicators. Annual statistics are cross-sectional data on business activities in the year in question. By contrast, business trend data have been made temporally comparable as concerns enterprise reorganisations and industry transfers so that the indicators describe changes in each industry.
Preliminary and final statistics are yearly published on structural business and financial statement statistics on the annual level. Preliminary data are completed in September of the year following the statistical reference year and final data in December.
The data of the statistics on industrial output describe production in Finland during the calendar year, while the data of the volume index of industrial output describe monthly data.

Only monthly data are published on the volume index of industrial output.

The data of the volume index of industrial output are used as source data for national accounts. In addition, the aim is to use uniform concepts and definitions with national accounts, as well as deflators compiled by national accounts in the production of the statistics.

The volume index of industrial output belongs to statistics on economic trends that describe short-term development in various factors and areas of the economy. The volume index of industrial output describes the change in industrial output at fixed prices on detailed industry level.

The data of the statistics cannot be fully compared with other indicators of output in manufacturing because the industry coverage is different in the statistics on new orders in manufacturing, for example.
 

Turnover data are used as source data for some industries in the production of the volume index of industrial output and total data are used for these industries.
In some industries, the value and volume data of output are still inquired in the data collection of industrial output and enterprises are selected based on sampling. For these industries, data are also supplemented with the Tax Administration's self-assessed taxation data. The methodological description of the statistics describes in more detail what source data are used in which industry.

Data for Statistics Finland's own data collection are gathered with a web questionnaire. In addition, Statistics Finland has agreed with the Tax Administration that the Tax Administration delivers the data on self-assessed taxes to Statistics Finland monthly on an agreed date.
The web questionnaire of the volume index of industrial output has been tested in connection with its introduction and when changes have been made to it. In addition, the non-response rate of the inquiry is monitored monthly.
 

The data of the volume index of industrial output are collected monthly.

In 2023, a total of 404 working days were used for the production of the volume index of industrial output.
An inquiry on the response burden of the statistics was made in spring 2018. The average response time for the inquiry of the statistics was 56 minutes.

Calculation of own data collection for the volume index of industrial output
The calculation of the statistics is started by calculating changes in the output volume of the establishment or enterprise from the production data of individual establishments or enterprises' various commodities. This is done in order to produce an unambiguous figure from volume and value data that describes the development of the establishment or enterprise. Commodity-specific data are weighted together by using the value of production from the previous year as the weight for each commodity. Value data are deflated in this stage.
In the next stage of the calculation, stratum-specific volume change data are formed by industry. The data on enterprises belonging to different size categories described above are combined by weighting together the data on enterprises in a certain size category belonging to the same industry. Either the values of the output of enterprises or establishments or the weights calculated based on the sampling design are used as weights.
After this, stratum-specific data are weighted together to the 3-digit level of the industrial classification. The obtained change data are used to chain the previous year's index forward so that the actual final industrial index is obtained at the 3-digit level of the industrial classification. The strata are weighted by using gross value data available from the total data of the regional statistics on entrepreneurial activity for enterprises in the stratum corresponding to the size category of enterprises.

Calculation based on turnover indices
For some industries, the volume index is calculated by expressing at constant prices the turnover index of the industry concerned. The calculation of turnover indices is based on estimation of change. Data cannot be calculated directly by summing, because the data are incomplete for the latest months: only part of enterprises are included. Comparable observations for the examined month and for the corresponding month of the previous year are compared in the method by observing enterprise reorganisations and changes in reporting practices related to bookkeeping. The indices are recalculated monthly until the data are final. Methodological time series modelling has been used to aid in the calculation of the latest months’ indices. This reduces the revision caused by the slow accumulation of data. The most recent month of the statistics is released at a delay of around six weeks.

Formation of published industries and index calculation
The industry indices at the 3-digit level can be used to calculate aggregate indices that combine various sub-industries as weighted averages of industry indices. The weight used in aggregation is the value added of the industry calculated from total data.
In Finland, the volume index of industrial output is calculated as a chain index with variable weights where the weight structure used in calculation is updated annually. The benefit of continuous updating is that the statistics reflect the structural changes in manufacturing as quickly as possible. The drawback is, for example, that the index point figures may become revised nearly two years backwards.
Although the index has no fixed base year, the data are published relative to a certain selected reference year for which the average of the indices of the original series is 100. The reference year is 2021 starting from the data for January 2024. The index point figures of earlier years have also been made comparable with the indices of the current reference year (2021=100).

The data of the volume index of industrial output are validated in several stages during the statistical process.
Validation of data of own data collection for the volume index of industrial output
The data are checked in every calculation round on the unit level by going through the most significant changes and deviating observations.

Validation of data based on turnover indices
The database based on the Tax Administration's data and Statistics Finland's sales inquiry is updated continuously. Systematic error types have been detected in certain variables, which are corrected even before the calculation. Due to data updates such as accumulation of data or changes in enterprises' monthly data, the calculated indices may change slightly from one calculation period to another. In the calculation stage of the indices, observations that prove to be erroneous are corrected or removed. The data are checked in each calculation round at the enterprise level against information about the most significant business reorganisations and changes in turnover, and enterprise openings and closures.
The revisions are examined in connection with the review process at the micro and macro levels. The special characteristics of different industries are also taken into account when the data are validated.

Seasonal adjustment is a statistical method used to process time series. The method is used to remove variation occurring fairly regularly within a year from the data. The Tramo/Seats method and J-Demetra+ software are used in the statistics. In addition, seasonal adjustment is based on the ESS Guidelines on Seasonal Adjustment.
The data of the volume index of industrial output are published as industry-specific index series. In addition to original series, indices are calculated as working day adjusted series and seasonally adjusted series as well as trend series.
By means of working-day adjusted indices, percentage changes can be calculated between different years by comparing the same months in different years. Changes within a year can be monitored by means of seasonally adjusted series and trend series. When using seasonally adjusted series and trend series it should be noted that in the Tramo/Seats method the latest months are partly based on model-based forecasts, so particular caution must be used in conclusions made based on them.
Further information about seasonal adjustment can be found in the methodological description of the statistics and in the report on seasonal adjustment with the Tramo/Seats method on Statistics Finland's home page.

The methodological description of the volume index of industrial output can be found on the home page of the statistics.
 

Statistics Finland

The compilation of statistics is guided by the Statistics Act. The Statistics Act contains provisions on collection of data, processing of data and the obligation to provide data. Besides the Statistics Act, the Data Protection Act and the Act on the Openness of Government Activities are applied to processing of data when producing statistics.

Statistics Finland compiles statistics in line with the EU’s regulations applicable to statistics, which steer the statistical agencies of all EU Member States. The statistics on the volume index of industrial output are guided by Regulation (EU) 2019/2152 of the European Parliament and of the Council on European business statistics and supplementing Commission Implementing Regulation (EU) 2020/1197.

Only the necessary data that are not available from administrative data sources are collected from data suppliers. Confidentiality is taken into account when data are published and it is ensured that the data or development of a single enterprise cannot be deduced on the basis of the results. The volume index of industrial output is one of the so-called sensitive statistics whose data can be treated before publication only by persons separately named by virtue of the Act on the Openness of Government Activities (Section 24, Paragraph 1, Sub-paragraph 13). The results are not released to users before the official date of publication of the statistics.
 

The data protection of data collected for statistical purposes is guaranteed in accordance with the requirements of the Statistics Act (280/2004), the Act on the Openness of Government Activities (621/1999), the EU's General Data Protection Regulation (EU) 2016/679 and the Data Protection Act (1050/2018). The data materials are protected at all stages of processing with the necessary physical and technical solutions. Statistics Finland has compiled detailed directions and instructions for confidential processing of the data. Employees have access only to the data essential for their duties. The premises where unit-level data are processed are not accessible to outsiders. Members of the personnel have signed a pledge of secrecy upon entering the service. Violation of data protection is punishable.

The publication of the volume index of industrial output does not include unit-level data. When calculating indices, applied are both the threshold rule, that is, the cell to be published must have at least three enterprises, and the dominance rule, that is, one unit must form under 80 per cent of the total value of the data to be published.
Industries 19, 20, 21, 22, 26, 27, 29 and 30 are not published separately because they contain dominant enterprises. They are published as combined industries and they are included in the figures for total industries (TOL BCD).
The data are submitted to Eurostat as confidential or flagged if there are three or fewer units on the publication level.

Statistics Finland publishes new statistical data at 8 am on weekdays in its web service. The release times of statistics are given in advance in the release calendar available in the web service. The data are public after they have been updated in the web service.

The data of the statistics are supplied monthly for the use of the Trend Indicator of Output and national accounts. In addition, the data of the statistics are supplied monthly to the use of Eurostat on the day of their publication and Eurostat releases the data on its web pages.

Statistical data are published as database tables in the StatFin database. The database is the primary publishing site of data, and new data are updated first there. When releasing statistical data, existing database tables can be updated with new data or completely new database tables can be published.

In addition to statistical data published in the StatFin database, a release on the key data is usually published in the web service. If the release contains data concerning several reference periods (e.g. monthly and annual data), a review bringing together these data is published in the web service. Database tables updated at the time of publication are listed both in the release and in the review. In some cases, statistical data can also be published as mere database releases in the StatFin database. No release or review is published in connection with these database releases.

Releases and database tables are published in three languages, in Finnish, Swedish and English. The language versions of releases may have more limited content than in Finnish.

Information about changes in the publication schedules of releases and database tables and about corrections are given as change releases in the web service.

Unit-level data of the statistics are used only for producing the statistics and others than producers of statistics do not have access to them.

Revisions –i.e. improvements in the accuracy of statistical data already published –are a normal feature of statistical production and result in improved quality of statistics. The principle is that statistical data are based on the best available data and information concerning the statistical phenomenon. On the other hand, the revisions are communicated as transparently as possible in advance. Advance communication ensures that the users can prepare for the data revisions.

The reason why data in statistical releases become revised is often caused by the data becoming supplemented. Then the new, revised statistical figure is based on a wider information basis and describes the phenomenon more accurately than before.

Revisions of statistical data may also be caused by the calculation method used, such as annual benchmarking or updating of weight structures. Changes of base years and used classifications may also cause revisions to data.
Seasonally adjusted data in statistics on economic trends become revised because of the calculation method used. Additional information on a new time series observation is exploited in model-based calculation methods and this is reflected as changes in previous releases. Revisions of the latest figures to be seasonally adjusted are elaborated on in the releases and quality reports of statistics.

A summary table of the revisions that have taken place is also published in connection with key statistics on economic trends and some annual statistics. The table shows how the data for the statistical reference periods have changed between the first and the most recent statistical release.

The data of the statistics are used at Eurostat, the European Central Bank (ECB) and in international organisations (e.g. OECD and UN) and in Finnish public administration to monitor and analyse the development of business services. Business and research institutes use the data to assess the development of markets and competitors. The data of the volume index of industrial output are also used as source data in the compilation of national accounts.

Eurostat assesses the data of the statistics yearly. The latest grade received by Finland was 10.

The quality of the volume index of industrial output is evaluated in several different stages of the statistical process. Revisions to the unit-level data of the statistics are examined monthly and coherence analyses are made with other statistics on economic trends.
Annual comparisons are made with the data of the statistics on industrial output.

Quality management requires comprehensive guidance of activities. The quality management framework of the field of statistics is the European Statistics Code of Practice (CoP). The quality criteria of Official Statistics of Finland are also compatible with the European Statistics Code of Practice.