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Plot a Profile Likelihood

Source: R/plots_extra.R
bd_profile_plot.Rd

Draws the profile log-likelihood produced by [bd_profile_ci()], with the critical threshold and the resulting interval marked.

Usage

bd_profile_plot(
  x,
  col = "steelblue",
  lwd = 2,
  main = NULL,
  xlab = NULL,
  ylab = NULL,
  ...
)

Arguments

x

An object of class `"bd_profile"`.

col, lwd

Colour and line width for the profile curve.

main, xlab, ylab

Labels. `NULL` uses sensible defaults.

...

Further graphical parameters.

Value

Invisibly returns `x`.

Details

The horizontal line sits at \(\ell_{\max} - \chi^2_{1,\alpha}/2\). Every parameter value whose profile lies above it is inside the interval.

When the curve does not fall back below that line before the right-hand edge of the grid, there is no finite upper bound and the plot says so. Widening the grid will not produce one; it will only confirm the flatness. That is the situation the underlying dissertation records for the tail index on the breaking-stress data.

See also

[bd_profile_ci()]

Examples

# \donttest{
dat <- simulate_bd_data(120, a = 1, b = 3, c = 2, k = 0.5, seed = 3)
fit <- fit_betadanish(survival::Surv(time, status) ~ 1, data = dat,
                      submodel = TRUE, n_starts = 1)
#> Warning: b-hat is only 1.89 standard errors from 1, close to the b = 1 non-identifiability ridge. Consider the ED submodel (submodel = TRUE). See the Identifiability section of ?fit_betadanish.
p <- bd_profile_ci(fit, "b", n_grid = 15L)
bd_profile_plot(p)

# }