lnorm_params {dampack}R Documentation

Calculate location and scale parameters of a log-normal distribution.

Description

Function to calculate the location, \mu, and scale, \sigma, parameteres of a log-normal distribution based on the method of moments (MoM) using the mean m and variance v of the non-logarithmized random variable of interest.

Usage

lnorm_params(m = 1, v = 1)

Arguments

m

Scalar with the mean of the random variable.

v

Scalar with the variance of the random variable. (i.e., squared standar error).

Value

A list containing the following:

mu Location parameter of log-normal distribution

sigma Scale parameter of log-normal distribution

Details

Based on method of moments. If m is the mean and v is the variance of the random variable, then the the location, \mu, and scale, \sigma, parameteres are computed as follows

\mu = \ln{(\frac{m}{\sqrt{(1 + \frac{v}{m^2})}})}

and

\sigma = \sqrt{\ln{( 1 + \frac{v}{m^2})}}

References

  1. Ginos BF. Parameter Estimation for the Lognormal Distribution. Brigham Young University; 2009.

  2. Log-normal distribution. (2017, April 20). In Wikipedia, The Free Encyclopedia. Retrieved 16:47, April 23, 2017, from https://en.wikipedia.org/w/index.php?title=Log-normal_distribution&oldid=776357974

Examples

m <- 3
v <- 0.01
lnorm_params(m, v)
# True values: 100, 30, 70

[Package dampack version 1.0.1 Index]