Statistical processing

Source data

The data used in Construction cost indices for civil engineering projects are mostly obtained from other statistics produced by Statistics Denmark.

Prices of materials are collected from the Price Index for Domestic Supply, which gathers prices from producers and importers on a monthly basis. Prices of transportation are collected quarterly from the Producer price index for services, from which prices of Freight transport by road are used. Other prices are collected from Net price index.

Labor costs are gathered from indices selected from Statistics Denmark's Standardised index of average earnings.

Up to April 2004 material and equipment costs were calculated on the basis of actual prices paid by producers/ importers excl. VAT. This means that the prices used were net of discounts of the actual sale of the materials or equipment. As of April 2004, the prices collected are the importers' purchasing price c.i.f. (i.e. including cost, insurance and freight) excl. taxes and fees, instead of the final sales prices that were collected previously.

The weight basis for this statistic was updated in 2025, with 2021 as base year. It was developed in cooperation with the Danish Road Directorate, Banedanmark and a number of entrepreneurs on the basis of an analysis of road construction work carried out in 2021. The weights reflect the shares of labor costs, material costs, transport costs and equipment costs of the total costs of performing civil-engineering projects. Approximately every fifth year, the weights are evaluated.

The indices for earth works, asphalt works, concrete structures and iron structures are used directly in the calculation of the cost index for construction of roads. The four indices have weights of 45,35 pct. for earth works, 25,24 pct. for asphalt works, 21,36 pct. for concrete structures and 8,05 pct. for iron structures.

Frequency of data collection

Primarily quarterly. In regards to product prices from the Price index for Domestic Supply, prices from the middle of the last month in the quarter represent the whole quarter.

Data collection

Prices from the Price Index for Domestic Supply and Producer Price Index for Services are reported digitally by select companies via http://www.Virk.dk

Labour costs in the Standardised Index of Average Earnings are collected quarterly via samples from private companies, as well as public wage systems.

Data validation

Basic data is validated before use in the Construction cost index for civil engineering projects. Price developments are tested for unusual and/or extreme changes. Prices that do not pass fixed threshold values will be checked manually by the staff and accepted only if the companies can verify the change.

When all prices are received, the system generates a list that includes all price changes and a measure of how these affects the elementary aggregates. The last validation is a visual inspection of all index tables.

Data compilation

The cost index for civil engineering projects is calculated following a hierarchical system where the collected prices are distributed into a number of product groups. These product groups are aggregated to "basic aggregate groups", which are used to calculate "basic prices". The developments between basic prices in subsequent time periods are used to calculate "basic indices", which is the most detailed index level. The basic indices are then used to calculate aggregated sub-indices using the Laspeyres type index formula. Finally, sub-indices are used to calculate main indices, which are the highest level in the index hierarchy.

For all indices, sub-indices for labor costs and a number of main cost groups are calculated. These sub-indices are weighed together to form the main indices. The process of weighing from individual prices through main indices is based on so-called classification codes and separate weights for each index type.

Index types include Construction of roads, Earth work, Asphalt work, Concrete structures, Iron structures, and Operating index. Sub-indices for Equipment and machinery, and for Freight transport by road are also compiled.

Adjustment

Substitution of the products used in calculation of the index may occur over time. Because such new products may be of a different quality than the previous, continuous quality control of is performed.

No other data corrections are carried out, except for the methods described in the sections for Data validation and Data compilation.