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Diagnostics attached to fitted values or response samples describe the coefficient chains before transformation or response simulation. Response noise can conceal poor mixing of coefficient chains. Use as_mcmc_draws() to examine particular derived quantities as well.

Usage

sampling_diagnostics(x)

# S3 method for class 'sampling_diagnostics'
print(x, ...)

Arguments

x

Output from a gratia sampling function; for the print method, a sampling_diagnostics object.

...

Further arguments passed to the print methods for the summaries.

Value

A sampling_diagnostics list with chains (acceptance rates and elapsed seconds), coefficients (posterior summaries, or NULL if not requested), and draws (a coefficient matrix with chain identities, or NULL if unavailable). Coefficient matrices provide their own draws; other sampling outputs need diagnostics = TRUE to retain them. Likelihood matrices from log_lik() also require diagnostics = TRUE for coefficient plots; use as_mcmc_draws() for their log-density draws.

Details

Coefficient draws are retained when sampling with diagnostics = TRUE, allowing draw.sampling_diagnostics() to plot the original coefficient chains even when x contains response samples, fitted values, smooths or derivatives. These plots do not describe the transformed quantities. Numerical summaries require posterior, but plotting does not.