twCoefLogitnorm: twCoefLogitnorm

In logitnorm: Functions for the Logitnormal Distribution

Description

Estimating coefficients of logitnormal distribution from median and upper quantile

Usage

twCoefLogitnorm(median, quant, perc = 0.975, method = "BFGS", 


    theta0 = c(mu = 0, sigma = 1), returnDetails = FALSE, 


    ...)

Arguments

median	numeric vector: the median of the density function
quant	numeric vector: the upper quantile value
perc	numeric vector: the probability for which the quantile was specified
method	method of optimization (see optim)
theta0	starting parameters
returnDetails	if TRUE, the full output of optim is attached as attributes resOptim
...

Value

numeric matrix with columns c("mu","sigma")

rows correspond to rows in median, quant, and perc

Author(s)

Thomas Wutzler

See Also

logitnorm

Examples

# estimate the parameters, with median at 0.7 and upper quantile at 0.9


(theta <- twCoefLogitnorm(0.7,0.9))





x <- seq(0,1,length.out=41)[-c(1,41)]	# plotting grid


px <- plogitnorm(x,mu=theta[1],sigma=theta[2])	#percentiles function


plot(px~x); abline(v=c(0.7,0.9),col="gray"); abline(h=c(0.5,0.975),col="gray")





dx <- dlogitnorm(x,mu=theta[1],sigma=theta[2])	#density function


plot(dx~x); abline(v=c(0.7,0.9),col="gray")





# vectorized


(theta <- twCoefLogitnorm(seq(0.4,0.8,by=0.1),0.9))

logitnorm documentation built on May 2, 2019, 6:15 p.m.