One of the difficulties in constructing growth and yield tables has been to determine which of the sample plots growing the same tree species and belonging to the same forest site type, with reference to the quality of stands, have to be included in the same growth series.
New growth and yield tables for the most important tree species were constructed in Finland in 1916–1919, using new principles that aim at avoiding some of the common weaknesses. There were two main differences to the earlier work. First, the site quality class (forest site type) was determined for each sample plot when the sample plot was measured, independently of the stand occupying the site. In this way it was possible to treat the sample plots of each site as an independent group from the beginning, and so that the quality classes were the same for all the tree species. Second, mathematic-statistical methods were used to deduct the so-called stem frequency distribution series, when studying which of the sample plots of the same quality class belong to the same growth series. They represent the average number of stems of the different diameter classes. A more detailed description of the method used to create the growth and yield tables is published in Acta Forestalia Fennica no. 15.
In the PDF is included a summary in Finnish.