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

## Description

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.

## Details

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`

Thomas Wutzler

## References

Frederic, P. & Lad, F. (2008) Two Moments of the Logitnormal Distribution. Communications in Statistics-Simulation and Computation, 37, 1263-1269

logitnorm documentation built on Dec. 9, 2017, 1:05 a.m.