dampack (version 1.0.2.1000)

lnorm_params: 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)

Value

A list containing the following:

mu Location parameter of log-normal distribution

sigma Scale parameter of log-normal distribution

Arguments

m

Scalar with the mean of the random variable.

v

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

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