Data of cost indices have been corrected retrospectively

Error concerned price data of diesel

Statistics Finland detected an error in October concerning the data for April to August 2026. The error was in the price data on diesel used in index calculation. The error concerns the cost index of civil engineering works, the cost index of road transport of goods, the cost index of bus and coach transport, the cost index for waste transport and the cost index for earth movers. In addition, the correction had an effect on the cost index of forest machinery and vehicles. Because the error was significant, the index was corrected retrospectively.

The erroneous data originated from the source data of the statistics. The error in the price data on diesel occurred at a time when market prices changed in other respects as well. This made it more difficult to detect the error. However, Statistics Finland is responsible for the calculation, quality assurance and open correction of errors relating to the indices it publishes.

Correction lowers index point figures

As a result of the correction, the point figures of the diesel fuel index decrease. The correction concerns all base years. The change has most effect on such indices where the weight of diesel fuel is high.

The corrections have been made to the database tables of the indices and the statistical releases of the cost index of civil engineering works.

Users should check the corrected figures if the indices have been used in calculations or agreement reviews during the period in question.

Retrospective correction may cause harm to users

Indices are widely used as a basis for index clauses in agreements. By means indices, agreement prices can be reviewed when costs change.

Correcting the data retrospectively may therefore cause additional work for index users and change needs for agreements. The effect of the corrected point figures depends on the index, period and agreement term used in each agreement. The parties to the agreement must assess the effects of the adjustment based on the terms of their own agreements.

“We apologise for the inconvenience caused to the index users by the error and the retrospective correction of the data. We understand that indices are the basis of many agreements and that corrections can cause additional work for users. However, the reliability of statistics requires that the detected errors are examined, corrected and reported openly,” says Deputy Director General Mari Ylä-Jarkko from Statistics Finland.

Quality assurance will be specified

Statistics Finland examines the chain of events leading to the error and goes through the quality assurance procedures related to the reception and verification of the source data and the index calculation.

The aim is to identify with which additional checks deviating price data could be detected and corrected before publishing the statistics.

Further information and corrected data

Change release of the cost index of civil engineering works on Statistics Finland's website:
⁠Cost index of civil engineering works: Database tables and publications corrected | Statistics Finland

Further information about chargeable databases is available upon request by email: kustannusindeksipalvelu@stat.fi.

The terms of agreement and use of chargeable statistical databases can be read on Statistics Finland's website:
⁠Terms of agreement and use of chargeable statistical databases | Statistics Finland

Contact information

Mari Ylä-Jarkko
⁠Deputy Director General, Information and Statistical Services
⁠+358 29 551 3880