## ter Braak C., Cormont A., Dray S. (2012).
*Improved testing of species traits-environment relationships
in the fourth corner problem*.
Ecology, 93:1525--1526.

The fourth-corner problem entails estimation and
statistical testing of the relationship between species
traits and environmental variables from the analysis of
three data tables. In a 2008 paper, S. Dray and P. Legendre
proposed and evaluated five permutation methods for
statistical significance testing, including a new two-step
testing procedure. However, none of these attained the
correct type I error in all cases of interest. We solve
this problem by showing that a small modification of their
two-step procedure controls the type I error in all cases.
The modification consists of adjusting the significance
level from sqrt(alpha) to alpha or, equivalently, of
reporting the maximum of the individual P values as the
final one. The test is also applicable to the three-table
ordination method RLQ.

[ |
]
Back

*This file was generated by
bibtex2html 1.98.*