Between-site covariance matrix Sigma_B (backward-compat wrapper)

Returns the implied between-unit trait covariance \(\Sigma_B = \Lambda_B \Lambda_B^\top + \boldsymbol\Psi_B\) and its correlation matrix. This is a thin wrapper around the unified extract_Sigma() function: equivalent to extract_Sigma(fit, level = "unit", part = "total") but with the historical Sigma_B / R_B field names.

Usage

extract_Sigma_B(fit)

Arguments

fit

A fit returned by gllvmTMB().

Value

A list with Sigma_B (T x T covariance), R_B (correlation), or NULL if no rr/diag term is present at the between-unit tier.

Details

Prefer extract_Sigma() for new code; that interface lets you ask for the rr-only "shared" component or the diag-only "unique" component, exposes the binomial-link implicit-residual option, and will be the entry point for 3+ rr tiers when the engine adds them.

See also

extract_Sigma() — the canonical unified API; pass level = "unit" for the same matrix.