Practices when changes are made to statistical data
The situations in which changes may be made to already published data can be divided into two groups: data revisions and release errors.
Data revisions improve the quality of statistics
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. 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 statistical data become revised is mostly caused by 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.
Seasonally adjusted data in statistics on economic trends become revised because of the calculation method used. Additional information from a new time series observation is exploited in model-based calculation methods and this is reflected as changes in previously released data. Revisions of the latest figures to be seasonally adjusted are explained in connection with statistical releases and in the documentation of the 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 releases.
The reasons for revisions in each set of statistics are given in the documentation of the statistics (under Data revision - practice). The description also explains the usual magnitude of the revisions, how long the data will be subject to revisions after their initial release, and whether certain data are subject to larger revisions than others.
If data are revised substantially more than usual, the reasons for it are separately explained in the release.
Users are informed about errors
Examples of errors in statistical releases include erroneous figures in release texts, figures or tables, or use of incorrect concepts. Unlike data revisions, error situations are unexpected deviations in the normal publication of statistics.
Errors are corrected and information is given about them as quickly as possible. Information about corrections is given in the release with change releases.
Typographical and other form errors in statistics are corrected as fast as possible and no separate notifications are made of them on the web pages.
Information about changes made to statistical databases is posted on the Changes in the StatFin database page.
Any change in the release time is indicated in Statistics Finland's release calendar.