Accuracy and reliability

Overall accuracy

The rent for residential units do not usually change significantly within a given quarter because it usually only changes when a new contract is signed or by regulating the rent which usually occurs in January. For the remaining categories, there is a greater degree of uncertainty associated with the statistical accuracy since the rent is subject to change during negotiations of the contract. The overall accuracy is deemed to be good.

Sampling error

It is not possible to quantify the statistical uncertainty in the rent indices for commercial real estate because the sample is not randomly drawn from the population. For the residential units, the sample consists of app. 110,000 property units out of a population of app. 500,000 units, hence there is a limited sample error. For the remaining categories, the coverage is lower and a higher statistical uncertainty is to be expected. The composition of the sample is compared with the composition of the population on a yearly basis with focus on geography, commercial use and rental conditions.

Non-sampling error

The sample for the rent indices for commercial real estate is continually evaluated against the Building and Residential register (BBR). In the case where there are errors in BBR, non-sampling error may occur. For categories other than residential, it is not possible to validate whether the property is rented or not and so it is harder to define the true population. It is therefore difficult to assess the true coverage. Improvements of the individual property unit are handled by set rules in the quality correction of the sample data. These rules are based on an evaluation and may contain measurement error with respect to the "true" change in rent where improvements of the property unit are accounted for.

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

There are no uncertainty related to the calculation, but there are some uncertainty overall due to the categories retail, offices and industry.

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 numbers are published.