beta_params {dampack}

Calculate alpha and beta parameters of beta distribution.

Description

Function to calculate the alpha and beta parameters of the beta distribution based on the method of moments using the mean \mu and standard deviation \sigma of the random variable of interest.

Usage

beta_params(mean, sigma)

Arguments

mean

mean of the random variable.

sigma

standard deviation of the random variable (i.e., standard error).

Value

a list containing the following:

alpha The method-of-moments estimate for the alpha parameter of the beta distribution

beta The method-of-moments estimate for the beta parameter of the beta distribution

Details

Based on methods of moments. If \mu is the mean and \sigma is the standard deviation of the random variable, then

\alpha = (\frac{1-\mu}{\sigma^2} - \frac{1}{\mu}) \mu^2

and

\beta = \alpha (\frac{1}{\mu} -1)