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actuar (version 0.9-3)

Paralogistic: The Paralogistic Distribution

Description

Density, distribution function, quantile function, random generation, raw moments and limited moments for the Paralogistic distribution with parameters shape and scale.

Usage

dparalogis(x, shape, rate = 1, scale = 1/rate, log = FALSE)
  pparalogis(q, shape, rate = 1, scale = 1/rate,
             lower.tail = TRUE, log.p = FALSE)
  qparalogis(p, shape, rate = 1, scale = 1/rate,
             lower.tail = TRUE, log.p = FALSE)
  rparalogis(n, shape, rate = 1, scale = 1/rate)
  mparalogis(order, shape, rate = 1, scale = 1/rate)
  levparalogis(limit, shape, rate = 1, scale = 1/rate,
               order = 1)

Arguments

x, q
vector of quantiles.
p
vector of probabilities.
n
number of observations. If length(n) > 1, the length is taken to be the number required.
shape, scale
parameters. Must be strictly positive.
rate
an alternative way to specify the scale.
log, log.p
logical; if TRUE, probabilities/densities $p$ are returned as $\log(p)$.
lower.tail
logical; if TRUE (default), probabilities are $P[X \le x]$, otherwise, $P[X > x]$.
order
order of the moment.
limit
limit of the loss variable.

Value

  • dparalogis gives the density, pparalogis gives the distribution function, qparalogis gives the quantile function, rparalogis generates random deviates, mparalogis gives the $k$th raw moment, and levparalogis gives the $k$th moment of the limited loss variable.

    Invalid arguments will result in return value NaN, with a warning.

Details

The Paralogistic distribution with parameters shape $= \alpha$ and scale $= \theta$ has density: $$f(x) = \frac{\alpha^2 (x/\theta)^\alpha}{ x [1 + (x/\theta)^\alpha)^{\alpha + 1}}$$ for $x > 0$, $\alpha > 0$ and $\theta > 0$.

The $k$th raw moment of the random variable $X$ is $E[X^k]$ and the $k$ limited moment at some limit $d$ is $E[\min(X, d)]$.

References

Klugman, S. A., Panjer, H. H. and Willmot, G. E. (2004), Loss Models, From Data to Decisions, Second Edition, Wiley.

Examples

Run this code
exp(dparalogis(2, 3, 4, log = TRUE))
p <- (1:10)/10
pparalogis(qparalogis(p, 2, 3), 2, 3)
mparalogis(2, 2, 3) - mparalogis(1, 2, 3)^2
levparalogis(10, 2, 3, order = 2)

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