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在林分自稀疏过程研究中，利用度量误差模型的形式估计林分断面积平均直径Ｄｇ与单位面积株数Ｎ关系模型的参数时，需要确定Ｄｇ和Ｎ的抽样误差ｅ、ε方差的比值。本文利用２０块人工落叶松标地的材料，经过再抽样，计算并比较了各种数据变换方式下，断面积平均直径与单位面积株数的方差比。结果表明ｌｎ（Ｎ）和Ｄｇ的方差比接近于常数，其均值为３．０２４８×１０－２。由此，可确定变量的变换形式和构造误差矩阵，从而为精确估计模型参数提供依据。
In the study of sparse stand process of forest stand, we need to determine the ratio of sampling deviations e and ε of Dg and N when estimating the parameters of the model of the relationship between the average diameter Dg of stands and the number of plant N per unit area using the measurement error model. In this paper, 20 Artificial Larch stock materials were used to calculate and compare the variance ratio of the average area of cross-sectional area to the number of units per unit area after resampling. The results show that the variance ratio of ln (N) to Dg is close to a constant with an average of 3.0248 × 10-2. Thus, the transformation form of variables and the construction error matrix can be determined, which provides the basis for accurate estimation of model parameters.