twCoefLogitnorm: twCoefLogitnorm In logitnorm: Functions for the Logitnormal Distribution

Description

Estimating coefficients of logitnormal distribution from median and upper quantile

Usage

 ```1 2``` ```twCoefLogitnorm(median, quant, perc = 0.975, ...) ```

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 `...`

Value

numeric matrix with columns `c("mu","sigma")` rows correspond to rows in median, quant, and perc

Author(s)

Thomas Wutzler

`logitnorm`
 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21``` ```# estimate the parameters, with median at 0.7 and upper quantile at 0.9 med = 0.7; upper = 0.9 med = 0.2; upper = 0.4 (theta <- twCoefLogitnorm(med,upper)) 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(med,upper),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(med,upper),col = "gray") # vectorized (theta <- twCoefLogitnorm(seq(0.4,0.8,by = 0.1),0.9)) .tmp.f <- function(){ # xr = rlogitnorm(1e5, mu = theta["mu"], sigma = theta["sigma"]) # median(xr) invlogit(theta["mu"]) qlogitnorm(0.975, mu = theta["mu"], sigma = theta["sigma"]) } ```