test_multiContrasts: Test multivariate contrasts
In rscherrer/sagreicolor:

Description Usage Arguments Value Note Author(s)

This function tests for significant contrasts between multivariate habitat-means within islands. The procedure is parametric and involves calculation of Wilk's lambda and P-value adjustment.

1	test_multiContrasts(W, specdata, vars, method = "bonferroni")

`W`	A matrix indicating all contrasts to be tested, or a vector if only one contrast. The number of rows is the number of contrasts to test. The number of columns is the number of groups. The matrix/vector is filled with zeros, except for a 1 and a -1 at the position of the groups that are to be contrasted.
`specdata`	A data frame containing at least columns for the dependent variables, as well as a column "island" and a column "habitat".
`vars`	A character or integer vector. The names, or indices, of the dependent variables in `specdata`.
`method`	Correction method for adjusting p-values.

A data frame with the results of each Wilk's lambda test in rows. In columns,

hab1, hab2 Habitats being compared.
Wilks Wilk's lambda.
approx.F F-value computed from Wilk's lambda.
df1, df2 Numerator and denominator degrees of freedom of the F distribution.
p.value P-value computed from the F-distribution.
p.adj Corrected P-value.

The parametric procedure was adapted from Charles Zaiontz's post on multivariate contrast testing in Excel: http://www.real-statistics.com/multivariate-statistics/multivariate-analysis-of-variance-manova/manova-follow-up-contrasts/.

Raphael Scherrer

rscherrer/sagreicolor documentation built on May 26, 2019, 12:32 p.m.