logitnorm-package: Utilities for the logitnormal distribution in R
In logitnorm: Functions for the Logitnormal Distribution

Description Details Author(s) References

Utilities for the logitnormal distribution in R

Density, distribution, quantile and random generation function.
Estimation of the mode and the first two moments.
Estimation of distribution parameters from observations.

The logitnormal distribution is useful as a prior density for variables that are bounded between 0 and 1, such as proportions. Fig. 1 displays its density for various combinations of parameters mu and sigma.

The package provides the main distribution functions:

density dlogitnorm,
distribution plogitnorm,
quantile qlogitnorm, and
random generation function rlogitnorm.

Transformation functions

(0,1) -> (-Inf,Inf): logit
(-Inf,Inf) -> (0,1): invlogit

Moments and mode

Expected value and variance: momentsLogitnorm
Mode: modeLogitnorm

Estimating parameters

from mode and upper quantile: twCoefLogitnormMLE
from mode and constraint to be unimodal and maximally flat: twCoefLogitnormMLEFlat
from median and upper quantile: twCoefLogitnorm
from expected value, i.e. mean and upper quantile: twCoefLogitnormE
from a confidence interval which is symmetric at normal scale: twCoefLogitnormCi
from prescribed quantiles: twCoefLogitnormN