Accuracy and reliability

Overall accuracy

The sample error of the total felling is about 2 percent. This figure is a measure for the sample error.

It is difficult to ascertain if there is any bias in the figures in the meaning of systematically too big or too small reported figures. The figures for the felling are compared with the area of wooded land.

Sampling error

The sample error of the total felling of tree was is about 2 per cent.

Non-sampling error

Coverage errors: A rather substantial over coverage Measurement errors: No information Non response: 1-3 percent Calculation errors: Not relevant Model assumptions: Not relevant

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 subject to certain sources of error:

• With respect to the register base there is a certain number of forestry farms which do not really have any wooded area but rather are agricultural farms or institutions with nature areas.
• The survey is subject to a normal sample error. The sample error of the total felling is about 2 per cent.
• The figures for the felling might be underestimated as it is more difficult to detect if the reported felling is too small than if it is too big.

By combining the extrapolation of the sample results into total results an acceptable quality is obtained. The total wooded area is known with a high degree of certainty.

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

Only final data are published.