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Accuracy and reliability

Contact info

Department of Social Statistics, Population and education
Annika Klintefelt
+45 39 17 36 78

akf@dst.dk

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Census of Housing

No investigation has been conducted on the overall accuracy and reliability, but the degree of unknown information on the dwellings are low. A close co-operation between the municipal authorities of the Register of Buildings and Dwellings and the Central Population Register ensures a high consistency between the addresses of the two registers.

Overall accuracy

A survey of the overall accuracy of the Register of Buildings and Dwellings has never been conducted. However, the degree of unknown variables is very small. According to the rules and regulations laid down by the Ministry of Economics and Business Affairs, public authorities and owners of buildings and dwellings are asked to provide information for maintaining the register. Owners are obliged to ensure that real and actual figures are continuously supplied. At the same time, the extensive administrative use of the register by the municipalities also insures a high data quality.

Quality and accuracy of information in the BBR:

Ownership: Before 2010 ownership information was not available for owner-occupied flats (se definition). In 2012 and 2013 there was a problem obtaining correct ownership on dwellings especially those owned by non-profit building societies and housing societies. This was caused by the Land Registration being digitized.

Use: The number of dwellings with the use as residential buildings for communities are not at all representative of the total number of dwellings for this purpose. These dwellings will most often be placed with use as terraced, linked or semi-detached houses or multi-dwelling houses.

The Central Register of Buildings and Dwellings was established in 1977 by compiling information collected from owners of real property. Figures on living space and time of construction for older buildings may be subject to errors. Especially in cases where the building has not later been involved in an administrative building or development case. This is, of course, due to the lack of accurate data by the owners as far back as 1977.

The accuracy of the Central Population Register is known to be very high. A close co-operation between the municipal authorities of the Central Register of Buildings and Dwellings and the Central Population Register ensures a high consistency between the addresses of the two registers.

The vast majority of CPR-addresses - 99.1* pct. - are matched perfect to a BBR-address with only one unit associated.

  • 99.6* pct. of the CPR-addresses are matched completely to an address in BBR.
  • 0.1* pct. of the CPR-addresses are matched to an empty dwelling at the same floor or same staircase.
  • 0.1* pct. of the CPR-addresses are aggregated with one or more CPR-addresses at the same floor
  • 0.2* pct. of the CPR-addresses find no dwelling in the BBR. These includes households on secret addresses and other not physical addresses ie. homeless, few allotment houses, houseboats and possibly new not yet completed dwellings.
  • 0.5* pct. of the population do not find a dwelling in the BBR-register.

*1. January 2017-data

Match of addresses on floor or stairway-level are considered as giving a good result at the overall level, but are not necessarily correct at the record level.

The number of unoccupied dwellings is very dependant on correct registration of units being registered and especially deregistered, when they are no longer available as dwellings.

Sampling error

Not applicable

Non-sampling error

Only a very little share of the population cannot be placed in a dwelling.

Quality management

Statistics Denmark follows the recommendations on organisation and management of quality given in the Code of Practice for European Statistics (CoP) and the implementation guidelines given in the Quality Assurance Framework of the European Statistical System (QAF). A Working Group on Quality and a central quality assurance function have been established to continuously carry through control of products and processes.

Quality assurance

Statistics Denmark follows the principles in the Code of Practice for European Statistics (CoP) and uses the Quality Assurance Framework of the European Statistical System (QAF) for the implementation of the principles. This involves continuous decentralized and central control of products and processes based on documentation following international standards. The central quality assurance function reports to the Working Group on Quality. Reports include suggestions for improvement that are assessed, decided and subsequently implemented.

Quality assessment

No real measure of quality is performed on the information in the Census of Housing. The vast majority of population is placed in a dwelling and the information in the BBR are considered reasonable. Most homeowners are not aware of the obligation to update the information in the BBR.

Known errors in the Census of Housing are:

-Problems getting correct ownership codes for the dwellings, especially in 2012 and 2013. Especially the number of dwellings owned by Non-profit building societies is too low (3-4 pct. in 2012) -Most of the residential buildings for communities are no longer registered with use as residential buildings for communities at the dwellings level. Since 2000 most of the Municipalities has changed the registration of the use of these dwellings which means that by 2014 there has been a 70 pct. decline in the number of these dwellings.
- The Municipality of Frederiksberg has registered far to many dwellings owned by non-profit building societies (25-30 pct.) in 2010-2015 - The Municipality of Svendborg had in 2010 error in tenure on approx. 20.000 dwellings, ie. 75 pct. of their dwellings. This has implications for the country total. - Some unoccupied student hostel dwellings in Copenhagen have been unoccupied since 2010, which means that these units probably are not used for this purpose anymore. - Some vacation rentals are in the BBR registered with use as as proper dwelling, which means that they in the census are counted as unoccupied dwellings.

Data revision - policy

Statistics Denmark revises published figures in accordance with the Revision Policy for Statistics Denmark. The common procedures and principles of the Revision Policy are for some statistics supplemented by a specific revision practice.

Data revision practice

Only final statistics are published.