Facts on the survey of silvicultural activities
Explanations regarding the statistics.
The statistics from the Swedish Forest Agency regarding silvicultural activities are based on two surveys: one random sample survey of small-scale forestry (owners of less than 5 000 hectares of forest land) and total population survey of large-scale forestry (owning more than 5 000 hectares). The survey of the large-scale forestry consists of more questions which is why for example the Pinus contorta regeneration is only known for this group. Taken together, the two separate surveys provide the most comprehensive picture of forestry operations in Sweden.
All estimates presented here have a statistical margin of error. The interval formed by the estimate and the margin of error is a 95% confidence interval. This means that if one were to repeat the survey, it would in 19 cases out of 20 cover the true (but unknown) value. The size of the interval depends on the number of observations in the sample and how widespread the variable is. The margins of error are usually not written in text but are available in the Swedish Forest Agency's statistics database together with the estimates. It has been included in the text above regarding clear-cutting forestry as variable has been surveyed a limited number of times which results in an increased uncertainty.