Add Confidence Region(s) for Quantiles and Probabilities

This function is used to add estimated confidence region(s) to an existing probability plot. Since confidence regions are related to the estimated regression line, the latter is provided as well.

plot_conf(p_obj, x, ...)

# S3 method for wt_confint
plot_conf(
  p_obj,
  x,
  title_trace_mod = "Fit",
  title_trace_conf = "Confidence Limit",
  ...
)

Arguments

p_obj

A plot object returned by plot_prob.

x

A tibble with class wt_confint returned by confint_betabinom or confint_fisher.

...

Further arguments passed to or from other methods. Currently not used.

title_trace_mod

A character string which is assigned to the model trace in the legend.

title_trace_conf

A character string which is assigned to the confidence trace in the legend.

Value

A plot object containing the probability plot with plotting positions, the estimated regression line and the estimated confidence region(s).

References

Meeker, William Q; Escobar, Luis A., Statistical methods for reliability data, New York: Wiley series in probability and statistics, 1998

Examples

# Reliability data:
data <- reliability_data(data = alloy, x = cycles, status = status)

# Probability estimation:
prob_tbl <- estimate_cdf(data, methods = "johnson")

# Example 1 - Probability Plot, Regression Line and Confidence Bounds for Three-Parameter-Weibull:
rr <- rank_regression(prob_tbl, distribution = "weibull3")

conf_betabin <- confint_betabinom(rr)

plot_weibull <- plot_prob(prob_tbl, distribution = "weibull")

plot_conf_beta <- plot_conf(
  p_obj = plot_weibull,
  x = conf_betabin
)

# Example 2 - Probability Plot, Regression Line and Confidence Bounds for Three-Parameter-Lognormal:
rr_ln <- rank_regression(
  prob_tbl,
  distribution = "lognormal3",
  conf_level = 0.9
)

conf_betabin_ln <- confint_betabinom(
  rr_ln,
  bounds = "two_sided",
  conf_level = 0.9,
  direction = "y"
)

plot_lognormal <- plot_prob(prob_tbl, distribution = "lognormal")

plot_conf_beta_ln <- plot_conf(
  p_obj = plot_lognormal,
  x = conf_betabin_ln
)

# Example 3 - Probability Plot, Regression Line and Confidence Bounds for MLE
ml <- ml_estimation(data, distribution = "weibull")

conf_fisher <- confint_fisher(ml)

plot_weibull <- plot_prob(prob_tbl, distribution = "weibull")

plot_conf_fisher_weibull <- plot_conf(
  p_obj = plot_weibull,
  x = conf_fisher
)