在二类森林资源调查中,南方重点林业县为保证小班调查值符合要求,均要求以抽样调查加以控制。这种抽样调查往往都是以县为总体,且往往在一类调查的固定样地上加密增加样本单元数量,以求达到规定的抽样精度要求。在抽样调查精度达到固定要求以后,小班调查值如超出抽样调查的置信区间但又符合允 In the second type of forest resources survey, the key forestry counties in the south require that they be controlled by sample surveys in order to ensure that survey values ​​in small classes meet the requirements. Such sampling surveys tend to be county-based in general and often increase the number of sample units on a fixed sample of surveys in order to achieve the required sampling accuracy. After the accuracy of the sample survey reaches a fixed requirement, the survey values ​​of small classes may exceed the confidence intervals of the sample survey but accord with the applicable standards