Extract variance-covariance of residuals 'Sigma'

Description

Extract the variance-covariance matrix of the residuals, usually noted

Σ

in PLN models. This captures the correlation between the species in the latent space.

Usage

## S3 method for class 'PLNfit'
sigma(object, ...)

Arguments

Value

A semi definite positive matrix of size p, assuming there are p species in the model.

See Also

coef.PLNfit(), standard_error.PLNfit() and vcov.PLNfit() for other ways to access

Σ

.

Examples

data(trichoptera)
trichoptera <- prepare_data(trichoptera$Abundance, trichoptera$Covariate)
myPLN <- PLN(Abundance ~ 1 + offset(log(Offset)), data = trichoptera)
sigma(myPLN) ## Sigma