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Implements an adaptive MCMC algorithm with component-wise updates and scale adaptation during burn-in.

Usage

AMCMC(
  theta_seed,
  nsim,
  eta = 0.6,
  adapt_frequency = 60L,
  init_scale = 1,
  proposal_dist = "normal"
)

Arguments

theta_seed

Initial parameter values

nsim

Total number of MCMC iterations

eta

Adaptation rate parameter, must be in (0.5, 1)

adapt_frequency

Frequency of scale adaptations (in iterations)

init_scale

Initial proposal scale (1/variance)

proposal_dist

Proposal distribution type, normal or student

Value

Matrix of MCMC samples (rows are iterations, columns are parameters)

Details

The algorithm uses component-wise Metropolis-Hastings updates with adaptive scaling during the burn-in period (first third of iterations). The scaling adapts to achieve approximately 36 percent acceptance rate per component.