Cost index of civil engineering works: documentation of statistics

The cost index of civil engineering works covers the most typical civil engineering works, which are:

• foundation structures
• earth structures
• rock structures
• surfacing
• municipal engineering systems
• concrete structures
• other technical systems

Indices are calculated for each work category by cost factor, which are:

• labour force
• own machinery
• purchased machinery services
• purchased transport services
• materials
• overhead site costs

The index is also calculated for crushing work, road maintenance, street maintenance, track maintenance and improvement of the rail line.

The statistical unit of the cost index of civil engineering works is a cost that must be paid by the contractor. A typical reporting unit from which data are collected is such as different enterprises selling materials or services to the contractor.

The population of the cost index of civil engineering works comprises all production factors used in civil engineering works.

The geographical reference area of the index of civil engineering works is the whole of Finland.

The length of the time series of the index varies depending on when the production of the index for the base year was started. Most of the time series start from 1990. The structure of the sub-indices has changed over time and they are not fully comparable for the whole time period.

The base year of the index currently used is 2020 (2020=100). The indices for the years 2010=100, 2015=100 and 2020=100 are structurally comparable. The base years of the indices have been the years 1963, 1972, 1980, 1985, 1990, 1995, 2000, 2005, 2010 and 2015.

Due to difficulties related to the acquisition of data, the cost indices for road and civil engineering works in the base years 1963, 1972, 1980 and 1985 were calculated mainly on the basis of the cost structure and input data of the Roads and Waterways Construction Administration. Thus, the old indices mainly depicted the price development of inputs used by the National Board of Public Roads in their own work and the index of machine work depicted development in the rental prices of machinery.

The data of the cost index of civil engineering works are released as index point figures. In addition, change percentages calculated based on the indices are also published. The base period is denoted by the number 100.

The index is updated monthly on the 23rd day of the month following the statistical reference month or on the following weekday. The price level of each month is compared with the price level of the base period. The annual index is published in connection with the release of the last month of the year.

The sub-indices are based on the INFRA 2006 Building Component and Project nomenclature and the structure of the INFRARYL 2006 general quality requirement system.

Sub-indices to be produced:

• foundation structures
• earth structures
• rock structures
• surfacing
• municipal engineering systems
• concrete structures
• technical and other systems
• crushing work
• maintenance
• road maintenance
• street maintenance
• track improvement

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 General Data Protection Regulation, 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.

Further information: Statistical legislation

The compilation of statistics is guided by the Statistics Act (280/2004). The Statistics Act contains provisions on collection of data, processing of data, confidentiality 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 (621/1999) are applied to processing of data when producing statistics. 

Further information: Statistical legislation

The released data are published monthly on the home page of the statistics as StatFin database tables.

On average, approximately 120 staff-days are spent yearly on producing the cost index of civil engineering works. The labour input comprises the collection, processing, analysis and publication of data.

In addition to a survey directed at enterprises, the calculation of the cost index of civil engineering works draws on other indices as well as information available on the websites of enterprises and organisations.

The response burden has been reduced by asking only one or a few price data items from enterprises in the questionnaire. Surveys are targeted at enterprises in a way that anticipates possible changes in price lists.

The calculation of the cost index of civil engineering works is based on Statistics Finland's own data collection of price data: Price inquiry for cost indices.

Other indices, such as the Consumer Price Index, the Producer Price Index for Manufactured Products, the building cost index and so on are also used in calculating the index.

The data for the cost index of civil engineering works are mainly collected monthly or less frequently.

A web questionnaire is used in the data collection. A reminder is sent to the respondents by email when the data collection has been opened. To some of the respondents an email questionnaire is sent, or price data are inquired by telephone. Some of the price data are collected directly from web pages or other indices are utilised.

The data of the cost index of civil engineering works are systematically validated. The calculation system puts price changes exceeding a certain threshold on the check list. In addition, missing observations or product changes reported by the data supplier are addressed.

If necessary, the data supplier is contacted or missing data are estimated. Changes in products can be treated in the calculation of the statistics by changing the price of the previous month so that the price paired comparison between two months is made for the same product standardised for quality.

As a rule, the previous price is used when price data are missing. Imputation is not used much in the calculation of the index of civil engineering works because the aim is to include all price observations in the calculation. Imputation is not used in the index due to the low number of price observations.

The checked observations form the statistical data. Price observations temporarily missing can be imputed with price changes of other corresponding products or the price of the previous month is used. An operator of the same size category is selected primarily as the new data provider for permanently missing price observations.

Index point figures are calculated with the base strategy utilising Laspeyres’ index formula. The observations are aggregated with weighting coefficients for products and data providers to the higher product group levels and finally into an overall index.

The users of the cost index of civil engineering works include civil engineering enterprises and organisations related to commissioning work in the civil engineering industry. They have their own representatives in the background group of index base year revisions. User needs, including those related to sub-indices and index classifications, are taken into account in connection with base year revisions.

There is no systematic monitoring of user satisfaction.

There are several possible sources of bias in the cost index for civil engineering works. These sources of bias include:

• sampling error
• deficient product and enterprise frames
• non-response
• quality changes in products included in the price collection and insufficient consideration of these in the compilation of the index
• substitution bias

Sampling error has not been defined.

The cost index of civil engineering works aims to reflect the price development of a product or service of consistent quality; therefore, changes in product quality or in its characteristics must be taken into account in index calculation.

The problem of quality change is usually encountered either when a data provider reports that a product included in the collection is no longer produced or that changes have been made to an existing product.

Quality changes can introduce errors into the index because it may be difficult to identify a genuine, pure price change and, conversely, it may be difficult to estimate and eliminate the part of the price change due to quality changes.

If, when a product is replaced, it is assumed that the entire price change is due to a change in the characteristics of the product, any genuine price change may be overlooked, whereby the index incorrectly does not change at all for the product in question. Conversely, if the entire price change is assumed to reflect a genuine price change, any change attributable to the product’s characteristics may be ignored, causing the index to change too much.

Non-response varies by month. The statistics aim at minimal non-response because price data cannot usually be imputed with other observations.

Potential processing errors in the index include the incorrect entry of manually recorded price data or the acceptance of price observations exceeding the margin of error.

Quality management requires comprehensive guidance of activities. The European Statistics Code of Practice forms the basis for the common quality system of the European Statistical System.

The Code of Practice is based on 16 principles that concern statistical authorities' independence, accountability and the quality of the processes and data to be published.

The principles are in line with the Fundamental Principles of Official Statistics approved by the United Nations Statistics Commission and are supplementary to them. The quality criteria of Official Statistics of Finland are compatible with the European Statistics Code of Practice.

Further information: European Statistics Code of Practice | Statistics Finland and Recommendations of the Advisory Board of Official Statistics of Finland | Statistics Finland

The quality of the cost index of civil engineering works is evaluated in several different stages of the statistical process. Changes in the unit level data of the statistics are examined monthly and the correctness of exceptional data is determined.

In connection with base year revisions, the background team approves the weight structure and sub-indices of the index.

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.

Cost index of civil engineering works is not revised (except only in error situations).

The cost index for civil engineering works is published on the 23rd day or the next weekday of the month following the statistical reference month.

The data are published on the days indicated in the release calendar.

An index that corresponds fully with the cost index of civil engineering works is not published in other countries. Statistics Sweden publishes, for example, an index of street lighting.

The base year of the index currently used is 2020 (2020=100). The sub-indices of the cost index of civil engineering works have changed over time. Since 2010 the sub-indices have remained unchanged.

The indices for civil engineering have been revised and at the same time the base year has been changed at times. The base years of the indices have been the years 1963, 1972, 1980, 1985, 1990, 1995, 2000, 2005, 2010 and 2015.

Due to difficulties related to the acquisition of data, the cost indices for road and civil engineering works in the base years 1963, 1972, 1980 and 1985 were calculated mainly on the basis of the cost structure and input data of the Roads and Waterways Construction Administration.

Thus, the old indices mainly depicted the price development of inputs used by the National Board of Public Roads in their own work and the index of machine work depicted development in the rental prices of machinery.

Annual level indices can be calculated from the monthly level indices of the cost index of civil engineering works.

National accounts use the cost index of civil engineering works as one deflator in their calculations.

The weight structure and sub-indices of the cost index of civil engineering works have changed for different base years. The same classification has been used in the current index 2020=100 as in the index 2015=100 and 2010=100. The indices of older base years differ structurally.

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 become public after they have been updated in the web service.

Further information: Publication principles for statistics at Statistics Finland

Statistics Finland's release calendar Future releases 

Future publications of the statistics can be found on the page of the statistics at: Future releases of the statistics

The data are released to all users at the same time. Statistical data may be processed at Statistics Finland and information on them may be given before release only by persons involved in the production of the statistics concerned or who need the data of the statistics concerned in their own work before the data are published.

Further information: Publication principles for statistics

Unless otherwise specifically stated in connection with the product, data or service concerned, Statistics Finland is the producer and copyright owner of the data. The terms of use for statistical data.

The statistics are published monthly on Statistics Finland’s web pages.

The release is published monthly on the home page of the statistics.

The database tables of the statistics can be found in the StatFin database.

Unit-level data of the statistics are used only for producing the statistics. No others than the producers of the statistics have access to unit-level material.

The weight structure of the base year 2020 can be found on the documentation page of the statistics. Methodological description is only available in Finnish.

The data protection of data collected for statistical purposes is guaranteed. The compilation of statistics is guided by the Statistics Act. Alongside the Statistics Act, the EU’s General Data Protection Regulation and the Finnish Data Protection Act are applied to the processing of personal data. Provisions on the confidentiality of data collected for statistical purposes are laid down in the Act on the Openness of Government Activities.

The data are processed only by persons who need the data in their work. The use of data is restricted by usage rights. All persons employed by Statistics Finland have signed a pledge of secrecy, where they have obliged to keep secret the data prescribed as confidential by virtue of the Statistics Act or the Act on the Openness of Government Activities.

Further information: Data protection | Statistics Finland (stat.fi)

The data of the cost index of civil engineering works can be handled only by persons involved in the production of the statistics. Enterprises acting as data providers or products’ price data are not published, but the published data are always aggregated index point figures comprised of several observations.