Accuracy and reliability

Overall accuracy

As the results are based on a sample survey, they are subject to a certain degree of statistical uncertainty. This depends on both the size of the sample and the number of completed interviews, which vary from survey to survey. With a sample of approximately 1,500 persons and a response rate of about 65 pct., which has normally been achieved in the last few years, the statistical uncertainty is in 95 pct. of the cases estimated to range between +/- 3 percentage points.

Sampling error

As the results are based on a sample survey, they are subject to a certain degree of statistical uncertainty. This depends on both the size of the sample and the number of completed interviews, which vary from survey to survey. With a sample of approximately 1,500 persons and a response rate of about 65%, which has normally been achieved in the last few years, the statistical uncertainty is in 95% of the cases estimated to range between +/- 3 percentage points.

Non-sampling error

These surveys are sample surveys in which a representative sample of persons between the ages of 16 and 74 are asked about their family's ownership of electronics in the home. The results have been corrected for biases in selection and nonresponse and are presented so that the figures can be directly attributed to the population of adults and families in Denmark. Measurement errors may occur in connection with the interviews, where interviewed individuals may misunderstand e.g. where to classify their respective education in the provided frames. Measurements errors are negligible, and have no impact on the results. Nonresponse will be corrected using the regression method. The weights are attached to each respondent so that population totals can be recreated/calculated from the sample.

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

For the time being the sample of an omnibus survey consists of 1,500 persons, drawn from a population of persons aged 16-74 residing in Denmark.

As it is not possible to interview all 1,500 persons, each completed interview is given a personal weight, which corrects the effects of non-sampling and non-response (including no telephone) and ensures that the results cover the whole population in the sample.

However, the questions on home appliances do not concern the individual person, but the family he/she is living with. For that reason the answers are given a family weight, which ensures that the families with different numbers of persons aged 16 years or over are represented in the sample with varying probability. A family is defined as one or several persons between 16 and 74 years who live in the same accommodation and are related (includes also cohabiting couples) and their children, though there can only be one married or cohabiting couple in the family. The sum of the family weight for all completed interviews, gives the number of families in Denmark that have persons aged between 16 and 74 years.

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

Provisional figures are not estimated.