Accuracy and reliability

Overall accuracy

The statistics are associated with a certain level of uncertainty, as especially very small consumptions can be difficult for the respondent to assess. Similarly, the consumption of wood, etc., not purchased in standard trade measures (from gardens, wood waste, gathering wood) is difficult to assess.

Sampling error

No sampling error has been calculated for the survey.

Non-sampling error

There will always be errors associated with sample-based and questionnaire-based statistics. The survey framework was reviewed and quality assured before distribution, but it is rare to avoid identifying sources of error afterward. To address the following sources of error, the dataset is reviewed to identify potential errors or to justify large consumptions, etc. In the wood survey, it is a source of uncertainty that respondents are unlikely to have a detailed record of wood consumption and may not fully understand the wood measurement units used (wood stacks, cubic meters, forest cubic meters, etc.). Consumption responses are therefore in some cases best estimates. Note, however, that wood measurements in the questionnaire are illustrated for the respondents. It can be difficult to convert how many wood baskets, number of days with a fire in the fireplace, or how much the woodpile has shrunk into the measurement units presented in the questionnaire.

People who primarily burn "other materials" (e.g., pallets, used wooden items) may not be able to answer the consumption questions accurately, as their consumption pattern is not measured in cubic meters. In future surveys, a free text field with the option to describe what is being burned and how much may improve the precision of the statistics. Misunderstanding of heating methods: It cannot be ruled out that some respondents simply do not know what type of stove they have in their home. In addition to this source of error, language difficulties must be mentioned, as the survey asks detailed questions about heating terms, heat sources, etc., which for people without a Danish upbringing can lead to misunderstandings.

Movements in the housing market: People move and may mistakenly answer for heating and consumption in a different home than the selected one.

Holiday homes and summerhouses with year-round occupancy: People who have registered their address in their (now) former holiday home may find it difficult to feel comfortable with the survey framework. In some cases, it may seem that the respondent answers that there is both a wood-burning stove in the home (where the address is registered) and in a holiday home, and it is assumed that this is a case of double counting (see section 5.2).
Responses with large consumption: For some households, wood-fired heating is the primary heating method, and therefore it is necessary in the survey framework to allow responses where a significant amount of wood consumption is reported.

There may be a bias in who chooses to respond to the survey. For example, it is conceivable that people who are particularly interested in the topic of "heating" respond to the questionnaire and that these have a particularly high or, conversely, particularly low rate of wood-burning stoves. Additionally, people without digital mail have not participated.

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 will always be errors associated with sample-based and questionnaire-based statistics. The survey framework was reviewed and quality assured before distribution, but it is rare to avoid identifying sources of error afterward.

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 statistics are new under Statistics Denmark, and there has been no need for revisions.