The Choice of Variables Transformation and Estimate of Measurement Error Matrix for the Study on Density diameter Relationship

It is necessary to determine the ratio between variance of sampling error e of quadratic average diameter Dg and that of sampling error ∈ of the tree numbers N per unit area when measurement error models is applied to estimate the parameters of a model between Dg and N,in a study on stand self thinning processes.This paper calculated and compared the variance ratios between transformd quadratic average diameter and transformd number of trees per unit area by using resampling from 20 larch plantation plots.The results show that the ratio between variance of ln( N ) and Dg approaches to a constant 3.0248 ×10-2. From the results,the best form of variable transformation is determined and the structure of error matrix is constructed,which can be used to get more accurate estimate of model parameters.