Smicroorganism的个人博客分享 http://blog.sciencenet.cn/u/Smicroorganism

博文

vegan包中RDA proportion of variance的计算

已有 1506 次阅读 2018-7-26 01:27 |个人分类:统计|系统分类:科研笔记

 https://www.davidzeleny.net/anadat-r/doku.php/en:rda_examples 

网址如上,内容如下

Call: rda(formula = spe.hell ~ pH + SOILDPT, data = env)

              Inertia Proportion Rank
Total         0.70476    1.00000     
Constrained   0.06250    0.08869    2
Unconstrained 0.64226    0.91131   94
Inertia is variance 

Eigenvalues for constrained axes:
   RDA1    RDA2 
0.04023 0.02227 

Eigenvalues for unconstrained axes:
    PC1     PC2     PC3     PC4     PC5     PC6     PC7     PC8 
0.07321 0.04857 0.04074 0.03144 0.02604 0.02152 0.01917 0.01715 
(Showed only 8 of all 94 unconstrained eigenvalues)

The two variables explain 8.9% of variance (the row Constrained and column Proportion in the table above, can be calculated also as the sum of eigenvalues for the contrained axes divided by total variance (inertia): (0.04023+0.02227) /0.70476=0.08868. The first constrained axis (RDA1) explains 0.04023/0.70476=5.7% of variance, while the second (RDA2) explains 0.02227/0.70476=3.2%. Note that the first unconstrained axis (PC1) represents 0.07321/0.70476=10.4% of total variance, which is more than both explanatory variables together; the first two unconstrained explain (0.07321+0.04857)/0.70476=17.3%. This means that the dataset may be structured by some strong environmental variable(s) different from pH and soil depth (we will check this below).



http://blog.sciencenet.cn/blog-1817482-1125943.html

上一篇:相关分析与回归分析
下一篇:反引号

0

该博文允许注册用户评论 请点击登录 评论 (1 个评论)

数据加载中...

Archiver|手机版|科学网 ( 京ICP备07017567号-12 )

GMT+8, 2020-7-3 07:35

Powered by ScienceNet.cn

Copyright © 2007- 中国科学报社

返回顶部