Accuracy and reliability

Overall accuracy

The statistics has been voluntary since 2004 and this has an impact on the coverage and validity. Before 2004 the survey was a total census aimed all marinas in Denmark. The change in the survey may have a negative consequence at the statistics.

Sampling error

Not relevant for this survey

Non-sampling error

The survey is collected on a voluntary basis and does therefore not provide a full coverage of nights spent in Danish marinas. Furthermore, some marinas will disseminate their questionnaires by the end of the year or too late for the monthly deadline, and their monthly numbers are subsequently imputed on the basis of the previous year. Reports can also be based on estimates by the respondents and therefore be less accurate. The number of nights spent at marinas is calculated by an average factor for the size of the crew in the boat. This factor is based on a survey made by VisitDenmark in 2017.

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 statistics is a census with voluntary participation from Danish marinas. Since the sample is relatively constant from year to year, the data are believed to be comparable from year to year. The variable number of overnight stays by nationality is considered most reliable.

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 monthly publications are preliminary and may differ from the final data in the annual publication that are published approx. 75 days after the end of the reference year.