Comparability
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Use of standards within the library in Denmark reflects both concrete Danish needs but also the organization of the international standard work. Statistics on public libraries are thus comparable with international statistics to the extent they are based on the same international standards.
For the research library statistics, data is comparable from 2009 onwards. For 2016, the questionnaire has been reduced. No comparison of these statistics has been made with corresponding international or foreign statistics.
The public school library statistics were published for the first time in 2022.
Comparability - geographical
The public and research library statistics are based on the quality standard for libraries (DS/ISO 2789). They are thus comparable to other international statistics for library activity.
Comparability over time
The public library statistics are comparable to previous publications, and at an overall level and for the municipalities that existed before the municipal reform in 2007. For information on public libraries' stock and use of electronic resources, comparable information is available from 2014. The individual-based library statistics were published for the first time in 2020. For the research library statistics, data is comparable from 2009 onwards. For 2016, the questionnaire has been reduced. Central variables such as lending and stock can still be traced back to 2009. The public school library statistics were published for the first time in 2022.
For the period 2020-2024 a person counted as a borrower at the public library, if for the given year that person had at least one loan in the library’s registration system as well as its registration was linked to a cpr-number. It has been possible to add to the public library data an extra identification variable – unilogin (an identification ID for students), which improves the identification of loans in the statistics from the year 2025 onwards. The addition of the unilogin to the data does not replace identification with the cpr-number, but instead, it adds an extra step in the identification of borrowers, for which their cpr-number is not available to start with. Where possible, the Unilogin is thus used to get hold of the cpr-number. The comparison of the number of loans in 2025 with and without the use of unilogin, shows that the use of unilogin allowed the identification of around 337.000 loans (an increase of 1,4pct.), which otherwise would not be accounted for in the statistics. Comparisons between the data from the public libraries for the period 2020-2024 with the data for the year of 2025 is therefore possible, but it should be taken into account that the method to identify loans has been improved from the year of 2025 and onwards.
Coherence - cross domain
The statistics are based on the DS/ISO 2789 standard, which is the international standard for compiling library statistics, and are thus comparable to other statistics for library activity. Statistics Denmark also compiles and publishes statistics on public libraries.
Coherence - internal
Not relevant