Accuracy and reliability

Overall accuracy

The statistics are believed to have a reasonable quality. The reported data are however assumed to be overvalued. This is based on our experience which shows that not all employee organisations are able to estimate the figures excluding members not attached to the labour market. In other words, students, early retirees and pensioners, as well as self-employed may be included . There is a risk that new small employee organisations have not been included in the population.

Sampling error

The statistics are based on an approximated census. There is a risk that newly established small employee organisations have not been included in the population.

Non-sampling error

The frame population is 110-120 Danish employee organisations, this number can change from year to year. One organisation do not report, which result in a minor under-coverage of less than 1 per cent.

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

A questionnaire is sent to those employee organisations which it have been identifiable. A single employee organisation (Danmarks Frie Fagforening) has never responded and number of members of the union is therefore not included in the statistics. Not all organisations are able to determine the figures exclusive members not attached to the labour market, i.e. there may be trainees, retirees and early retirees included in the figures as well as self-employed. To the extent that organisations are able to correct errors previously reported, the figures are corrected to the extent that it is possible, however this is often difficult for historic data. No figures are available regarding the size of insecurity. Quality is assessed to be reasonable.

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

Normally the published figures are not revised. If errors are detected in the published figures, these will, however, be corrected.