call_log_posterior_m: Metropolis Acceptance Step for Vectorized MCMC Sampling

In dRiftDM: Estimating (Time-Dependent) Drift Diffusion Models

Metropolis Acceptance Step for Vectorized MCMC Sampling

Description

This internal function computes the Metropolis acceptance decision for a set of MCMC proposals, using either hierarchical or non-hierarchical posterior evaluation. It returns updated log-posterior and log-likelihood values, as well as a logical vector indicating accepted proposals.

Usage

call_log_posterior_m(
  proposal_mat,
  prev_prms_mat,
  prev_pis,
  prev_lls,
  level,
  re_eval,
  ...
)

Arguments

proposal_mat	a numeric matrix of proposed parameter values. Each column corresponds to one chain; rows represent parameters.
prev_prms_mat	a numeric matrix of current (previous) parameter values. Must have the same dimensions as proposal_mat.
prev_pis	a numeric vector of current log-posterior values for each chain.
prev_lls	a numeric vector of current log-likelihood values for each chain.
level	a character string specifying the sampling level, either "lower", "hyper", or "none". Determines whether to call log_posterior_lower() or log_posterior_hyper().
re_eval	logical. If TRUE, the log-posterior and log-likelihood for the current parameters are re-evaluated.
...	Additional arguments passed to log_posterior_lower() or log_posterior_hyper(), depending on the level.

Details

This function implements a vectorized Metropolis acceptance step for multiple MCMC chains simultaneously. The posterior is calculated using either log_posterior_lower() for subject-level parameters or log_posterior_hyper() for group-level parameters.

Log-posterior and log-likelihood values are only updated where proposals were accepted. In cases where proposals yield invalid posteriors (i.e., NA), they are automatically rejected.

Value

A list with three elements:

pis

A numeric vector of updated log-posterior values.

lls

A numeric vector of updated log-likelihood values.

accept

A logical vector of length equal to the number of chains, indicating which proposals were accepted.

dRiftDM documentation built on Dec. 1, 2025, 5:08 p.m.