Density, distribution function, quantile function, hazard function,
cumulative hazard function, and random
generation for the Loglogistic distribution with parameters shape
and scale.
dllogis(x, shape = 1, scale = 1, log = FALSE)
pllogis(q, shape = 1, scale = 1, lower.tail = TRUE, log.p = FALSE)
qllogis(p, shape = 1, scale = 1, lower.tail = TRUE, log.p = FALSE)
hllogis(x, shape = 1, scale = 1, prop = 1, log = FALSE)
Hllogis(x, shape = 1, scale = 1, prop = 1, log.p = FALSE)
rllogis(n, shape = 1, scale = 1)vector of quantiles.
vector of probabilities.
number of observations. If length(n) > 1, the length
is taken to be the number required.
shape and scale parameters, both defaulting to 1.
A 'proportional hazards' parameter, for now only available
for hllogis and Hllogis. See Details.
logical; if TRUE, probabilities p are given as log(p).
logical; if TRUE (default), probabilities are \(P[X \le x]\), otherwise, \(P[X > x]\).
dllogis gives the density,
pllogis gives the distribution function,
qllogis gives the quantile function,
hllogis gives the hazard function,
Hllogis gives the cumulative hazard function, and
rllogis generates random deviates.
Invalid arguments will result in return value NaN, with a warning.
The Loglogistic distribution with shape parameter \(a\) and
scale parameter \(\sigma\) has density given by
$$f(x) = (a/\sigma) {(x/\sigma)}^{a-1} / (1 + {(x/\sigma)}^{a})^2$$
for \(x \ge 0\).
The cumulative distribution function is
\(F(x) = 1 - 1 / (1 + {(x/\sigma)}^a)\)
on \(x \ge 0\).
From eha version 2.3-0, the loglogistic distribution is extended to a three-parameter family of distributions. The third parameter, 'prop', is a 'proportional hazards' parameter, simply multiplying the hazard function by its value. For now only implemented in the hazard and cumulative hazards functions, but it will be introduced fully soon. Probably as a class of distributions with a new name.
See also phreg.