distr6 (version 1.3.6)

Weibull: Weibull Distribution Class

Description

Mathematical and statistical functions for the Weibull distribution, which is commonly used in survival analysis as it satisfies both PH and AFT requirements.

Value

Returns an R6 object inheriting from class SDistribution.

Constructor

Weibull$new(shape = 1, scale = 1, altscale = NULL, decorators = NULL, verbose = FALSE)

Constructor Arguments

Argument	Type	Details
shape	numeric	shape parameter.
scale	numeric	scale parameter.
altscale	numeric	alternative scale parameter.

decorators Decorator decorators to add functionality. See details.

Constructor Details

The Weibull distribution is parameterised with shape, scale, and altscale as positive numerics.

Public Variables

Variable	Return
name	Name of distribution.
short_name	Id of distribution.
description	Brief description of distribution.

Public Methods

Accessor Methods	Link
decorators	decorators
traits	traits
valueSupport	valueSupport
variateForm	variateForm
type	type
properties	properties
support	support
symmetry	symmetry
sup	sup
inf	inf
dmax	dmax
dmin	dmin
skewnessType	skewnessType
kurtosisType	kurtosisType

Statistical Methods Link pdf(x1, ..., log = FALSE, simplify = TRUE) pdf cdf(x1, ..., lower.tail = TRUE, log.p = FALSE, simplify = TRUE) cdf quantile(p, ..., lower.tail = TRUE, log.p = FALSE, simplify = TRUE) quantile.Distribution rand(n, simplify = TRUE) rand mean() mean.Distribution variance() variance stdev() stdev prec() prec cor() cor skewness() skewness kurtosis(excess = TRUE) kurtosis entropy(base = 2) entropy mgf(t) mgf cf(t) cf pgf(z) pgf median() median.Distribution iqr() iqr mode(which = "all") mode

Parameter Methods Link parameters(id) parameters getParameterValue(id, error = "warn") getParameterValue setParameterValue(..., lst = NULL, error = "warn") setParameterValue

Validation Methods Link liesInSupport(x, all = TRUE, bound = FALSE) liesInSupport liesInType(x, all = TRUE, bound = FALSE) liesInType

Representation Methods Link strprint(n = 2) strprint print(n = 2) print summary(full = T) summary.Distribution

Details

The Weibull distribution parameterised with shape, \(\alpha\), and scale, \(\beta\), is defined by the pdf, $$f(x) = (\alpha/\beta)(x/\beta)^{\alpha-1}exp(-x/\beta)^\alpha$$ for \(\alpha, \beta > 0\).

The distribution is supported on the Positive Reals.

mgf and cf are omitted as no closed form analytic expression could be found, decorate with CoreStatistics for numerical results.

References

McLaughlin, M. P. (2001). A compendium of common probability distributions (pp. 2014-01). Michael P. McLaughlin.

See Also

listDistributions for all available distributions. Frechet and Gumbel for other special cases of the generalized extreme value distribution. CoreStatistics for numerical results.

Examples

# NOT RUN {
# Different parameterisations
Weibull$new(shape = 1, scale = 2)
Weibull$new(shape = 2, altscale = 2)

x <- Weibull$new(shape = 2, scale = 3)

# Update parameters
x$setParameterValue(scale = 1)
x$parameters()

# d/p/q/r
x$pdf(5)
x$cdf(5)
x$quantile(0.42)
x$rand(4)

# Statistics
x$mean()
x$variance()

summary(x)

# }