Defining Johnson-Neyman regions of significance in the three-covariate ANCOVA using mathematica
Defining Johnson-Neyman regions of significance in the three-covariate ANCOVA using mathematica
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DOI：
10.2307/1165228
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发表时间：
1997-12-01
影响因子：
2.4
通讯作者：
Leighton, J
中科院分区：
文献类型：
--
作者：
Hunka, S;Leighton, J
当存在组内回归的非齐性时，使用Johnson-Neyman ANCOVA，当使用三个协变量时，提出了特殊的计算rind标绘问题。这些问题可以通过使用(A)一般线性模型的适当设计和对比矩阵以及(B)处理符号和图形处理要求的数学软件计算系统来克服。多项式的四维图形表示，其结果是在三维空间中绘制等高线，以便定义对比度的重要区域。文中还表明，对于协变量的某些值，可以产生正交性对比。
The Johnson-Neyman ANCOVA, used when nonhomogeneity of within-group regressions is present, poses special computational rind plotting problems when three covariates are used. These problems can be overcome by using (a) an appropriate design and contrast matrix for the general linear model and (b) the Mathematica software system of computation to handle the symbolic and graphical processing requirements. Four-dimensional graphical representation of the polynomials which result are contour plotted in a three-dimensional space in order to define the regions of significance for contrasts. It is also shown that for some values of the covariate orthogonal contrasts are produced.