Statistical processing

Source data

Information from questionnaires from forestry farms. The statistics are based on a questionnaire survey among Danish forests with at least 0.5 ha of forest.

Frequency of data collection

Yearly.

Data collection

The survey is based on questionnaires. The questionnaire has to be completed online.

Data validation

The survey is validated in three different steps:

When completing the questionnaire online all questions must be answered.

In the next step the answers are checked for unrealistic values. Mistakes are corrected immediately, sometimes after having contacted the owner of the forestry by phone.

In the last step the results by regions are studied. In this step it will often be possible to find a few big mistakes which have been overlooked in the first two steps.

Data compilation

The survey is a stratified sample survey where the stratification has three dimensions:

Size with wood land, five groups:

• 0.5-4.9 ha
• 5.0-19.9 ha
• 20.0-49.9 ha
• 50.0-99.9 ha
• 100.0 ha and over

Four regions:

• East Denmark
• Region Syddanmark
• Midtjylland
• Nordjylland

The smallest of forests of 0,5-4,9 hectares constitutes one stratum only irrespective of region, and thereby has sample all in all 17 strata. The sample is extrapolated to a total level by choosing the area with forest in Denmark as target. The area with forestry is calculated by Institute for Geo Science and Nature at the University of Copenhagen.

For the 2017 and the 2019-survey the results for the small forests have been estimated and they have thereby not received a questionnaire.

Adjustment

No adjustments bedsides what is described in “Data validation and “Data analysis”.