Parametric Monte Carlo draws from a TMB fit's asymptotic posterior

Draws R samples of the internal-scale fixed-effect parameter vector from the joint asymptotic Gaussian posterior \(N(\hat\beta, \hat\Sigma)\), where \(\hat\beta\) is object$model$coefficients and \(\hat\Sigma\) is vcov(object) (the TMB sdreport fixed-effect covariance, sdr$cov.fixed). The mean vector and covariance are positionally aligned because both derive from the optimizer's opt$par.

Usage

.tmb_parametric_draws(object, R = 1000L, seed = NULL)

Arguments

object

A beezdemand_tmb object.

R

Integer number of Monte Carlo draws.

seed

Optional integer seed. When supplied, the caller's RNG state is saved and restored so the global .Random.seed stream is left unperturbed.

Value

Numeric matrix of dimension R x p, with columns named after the internal coefficient vector (names(object$model$coefficients)).

Details

This is the shared primitive behind confint(object, method = "simulate") and is intended for reuse by derived-metric bootstrap helpers. Draws are fixed-effect-only on the internal scale; callers transform to the natural scale or evaluate derived metrics as needed.

The symmetric matrix square root is formed via an eigendecomposition with negative eigenvalues clamped to zero, matching MASS::mvrnorm's robustness to a near-semidefinite covariance without taking a dependency.