Definition:Reference unit

The reference unit defines a hierachy in Heureka's forest model. It is typically a circular sample plot, at which all trees have been measured. A treatment unit can be represented by survey plots actually measured for the unit, or indirectly by survey plots imputed (assigned or copied) to the the unit through kNN methods. To distinguish between "true" plots, and imputed (assigned) plots, the reference unit is linked to a treatment unit through the cell object.