Extract Model Constrained/Canonical Coefficients
concoef is a generic function which extracts the constrained
(canonical) coefficients from objects returned by certain modelling
functions.
concoef(object, ...)
object |
An object for which the extraction of canonical coefficients is meaningful. |
... |
Other arguments fed into the specific methods function of the model. |
For constrained quadratic and ordination models, canonical coefficients are the elements of the C matrix used to form the latent variables. They are highly interpretable in ecology, and are looked at as weights or loadings.
They are also applicable for reduced-rank VGLMs.
The value returned depends specifically on the methods function invoked.
concoef replaces ccoef;
the latter is deprecated.
For QO models, there is a direct inverse relationship between the
scaling of the latent variables (site scores) and the tolerances.
One normalization is for the latent variables to have unit variance.
Another normalization is for all the species' tolerances to be
unit (provided eq.tolerances is TRUE). These two
normalizations cannot simultaneously hold in general. For rank
R models with R>1 it becomes more complicated because
the latent variables are also uncorrelated. An important argument when
fitting quadratic ordination models is whether eq.tolerances
is TRUE or FALSE. See Yee (2004) for details.
Thomas W. Yee
Yee, T. W. and Hastie, T. J. (2003). Reduced-rank vector generalized linear models. Statistical Modelling, 3, 15–41.
Yee, T. W. (2004). A new technique for maximum-likelihood canonical Gaussian ordination. Ecological Monographs, 74, 685–701.
Yee, T. W. (2006). Constrained additive ordination. Ecology, 87, 203–213.
concoef-method,
concoef.qrrvglm,
concoef.cao,
coef.
## Not run: set.seed(111) # This leads to the global solution
hspider[,1:6] <- scale(hspider[,1:6]) # Standardized environmental vars
p1 <- cqo(cbind(Alopacce, Alopcune, Alopfabr, Arctlute, Arctperi,
Auloalbi, Pardlugu, Pardmont, Pardnigr, Pardpull,
Trocterr, Zoraspin) ~
WaterCon + BareSand + FallTwig + CoveMoss + CoveHerb + ReflLux,
family = poissonff, data = hspider, Crow1positive = FALSE)
concoef(p1)
## End(Not run)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.