Accuracy and reliability

Overall accuracy

Although the survey is well established, it has a relatively high non-response rate, resulting in a small net sample and consequently greater statistical uncertainty. In addition, certain socio-economic groups may be overrepresented, as they are more likely than others to participate in the survey. It has also been found that travel patterns differ between older respondents who complete the web survey and those who participate in telephone interviews (CATI). For these reasons, an increasing use is made of mixed-mode data collection, in which different data collection methods complement one another and help reduce potential bias. As the survey has also undergone substantial methodological changes over time, the results are currently not considered suitable for time series analysis.

Sampling error

Not calculated.

Non-sampling error

Not calculated.

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

The survey is a sample survey of the travel behavior of the Danish population. The estimates are based on information reported by persons registered in the Danish Civil Registration System (CPR). The survey has a relatively high non-response rate, resulting in a small net sample and consequently greater statistical uncertainty. In addition, certain socio-economic groups may be overrepresented, as they are more likely than others to participate in the survey. The survey has undergone a number of methodological changes over time, which limits its suitability for time series analysis. Consequently, the results should primarily be regarded as a snapshot of the level of tourism activity rather than as a basis for analysing trends over time. The variables measuring the number of trips and preferred destinations are considered the most reliable. Estimates of travel expenditure are subject to greater uncertainty, as respondents often have difficulty recalling their spending and other details of their trips.

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

The published statistics are final and are not subsequently revised unless errors are identified in the data.