cdfrevgum {lmomco} | R Documentation |
This function computes the cumulative probability or nonexceedance probability
of the Reverse Gumbel distribution given parameters (xi and α) of the distribution computed
by parrevgum
. The cumulative distribution function of the distribution is
F(x) = 1 - e^{-e^{(-frac{(x-xi)}{α})}} mbox{,}
where F(x) is the nonexceedance probability for quantile x,
xi is a location parameter, and α is a scale parameter. Notice that the function has some sign differences and uses the complement of F compared to the cumulative distribution function of the Gumbel distribution in cdfgum
.
cdfrevgum(x, para)
x |
A real value. |
para |
The parameters from parrevgum or similar. |
Nonexceedance probability (F) for x.
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.
# See p. 553 of Hosking (1995) # Data listed in Hosking (1995, table 29.3, p. 553) D <- c(-2.982, -2.849, -2.546, -2.350, -1.983, -1.492, -1.443, -1.394, -1.386, -1.269, -1.195, -1.174, -0.854, -0.620, -0.576, -0.548, -0.247, -0.195, -0.056, -0.013, 0.006, 0.033, 0.037, 0.046, 0.084, 0.221, 0.245, 0.296) D <- c(D,rep(.2960001,40-28)) # 28 values, but Hosking mentions 40 values in total z <- pwmRC(D,threshold=.2960001) str(z) # Hosking reports B-type L-moments for this sample are # lamB1 = -0.516 and lamB2 = 0.523 btypelmoms <- pwm2lmom(z$Bbetas) # My version of R reports lamB1 = -0.5162 and lamB2 = 0.5218 str(btypelmoms) rg.pars <- parrevgum(btypelmoms,z$zeta) str(rg.pars) # Hosking reports xi=0.1636 and alpha=0.9252 for the sample # My version of R reports xi = 0.1635 and alpha = 0.9254 F <- nonexceeds() PP <- pp(D) # plotting positions of the data D <- sort(D) plot(D,PP) lines(D,cdfrevgum(D,rg.pars))