lmomco (version 0.88)

parwei: Estimate the Parameters of the Weibull Distribution

Description

This function estimates the parameters of the Weibull distribution given the L-moments of the data in an L-moment object such as that returned by lmom.ub. The Weibull distribution is a reverse Generalized Extreme Value distribution. As result, the Generalized Extreme Value algorithms are used for implementation of the Weibull in this package. The relation between the Generalized Extreme Value parameters ($\xi$, $\alpha$, and $\kappa$) is

$$\kappa = 1/\delta \mbox{,}$$

$$\alpha = \beta/\delta \mbox{, and}$$

$$\xi = \zeta - \beta \mbox{.}$$

These relations are taken from Hosking and Wallis (1997).

Usage

parwei(lmom,checklmom=TRUE)

Arguments

lmom

A L-moment object created by lmom.ub or pwm2lmom.

checklmom

Should the lmom be checked for validity using the are.lmom.valid function. Normally this should be left as the default and it is very unlikely that the L-moments will not be viable (particularly in the $\tau_4$ and $\tau_3$ inequ

Value

• An R list is returned.
• type
  The type of distribution: wei.
• para
  The parameters of the distribution.
• source
  The source of the parameters: parwei.

References

Hosking, J.R.M. and Wallis, J.R., 1997, Regional frequency analysis---An approach based on L-moments: Cambridge University Press.

See Also

lmom.ub, lmomwei, cdfwei, quawei

Examples

lmr <- lmom.ub(rnorm(20))
parwei(lmr)
lmr <- parwei(lmom.ub(rweibull(3000,1.3,scale=340)-1200))
str(lmr)