lmomgpaRC {lmomco} | R Documentation |
This function computes the “B”-type L-moments of the Generalized Pareto distribution
given the parameters (xi, α, and kappa) from pargpaRC
and the right-tail censoring fraction zeta.
The B-type L-moments in terms of the parameters are
λ^B_1 = xi + α m_1 mbox{,}
λ^B_2 = α (m_1 - m_2) mbox{,}
λ^B_3 = α (m_1 - 3m_2 + 2m_3)mbox{,}
λ^B_4 = α (m_1 - 6m_2 + 10m_3 - 5m_4)mbox{, and}
λ^B_5 = α (m_1 - 10m_2 + 30m_3 - 35m_4 + 14m_5)mbox{,}
where m_r = lbrace 1-(1-zeta)^{r+kappa}rbrace/(r+kappa) and zeta is the right-tail censor fraction or the probability mathrm{Pr}lbrace rbrace that x is less than the quantile at zeta nonexceedance probability: (mathrm{Pr}lbrace x < X(zeta) rbrace). Finally, the RC
in the function name is to denote R
ight-tail C
ensoring.
lmomgpaRC(para)
para |
The parameters of the distribution. Note that if the zeta part of the parameters (see pargpaRC ) is not present then zeta=1 is assumed. |
An R list
is returned.
lambdas |
Vector of the L-moments. First element is λ_1, second element is λ_2, and so on. |
ratios |
Vector of the L-moment ratios. Second element is tau, third element is tau_3 and so on. |
source |
An attribute identifying the computational source of the L-moments: “lmomgpa2”. |
message |
For clarity, this function adds the unusual message to an L-moment object that the lambdas and ratios are B-type L-moments. |
zeta |
The censoring fraction. Assumed equal to unity if not present in the gpa parameter object. |
W.H. Asquith
Hosking, J.R.M., 1990, L-moments—Analysis and estimation of distributions using linear combinations of order statistics: Journal of the Royal Statistical Society, Series B, vol. 52, p. 105–124.
Hosking, J.R.M., 1995, The use of L-moments in the analysis of censored data, in Recent Advances in Life-Testing and Reliability, edited by N. Balakrishnan, chapter 29, CRC Press, Boca Raton, Fla., pp. 546–560.
pargpa
, pargpaRC
, lmomgpa
, quagpa
, cdfgpa
para <- vec2par(c(1500,160,.3),type="gpa") # build a GPA parameter set lmorph(lmomgpa(para)) lmomgpaRC(para) # zeta = 1 is internally assumed if not available # The previous two commands should output the same parameter values from # independent code bases. # Now assume that we have the sample parameters, but the zeta is nonunity. para$zeta = .8 lmomgpaRC(para) # The B-type L-moments.