mom_beta function

Method of moments for beta distribution

Method of moments for beta distribution

Compute the parameters shape1 and shape2 of the beta distribution using method of moments given the mean and standard deviation of the random variable of interest.

mom_beta(mean, sd)

Arguments

  • mean: Mean of the random variable.
  • sd: Standard deviation of the random variable.

Returns

A list containing the parameters shape1 and shape2.

Details

If μ\mu is the mean and σ\sigma is the standard deviation of the random variable, then the method of moments estimates of the parameters shape1 = α>0\alpha > 0 and shape2 = β>0\beta > 0 are:

α=μ(μ(1μ)σ21) \alpha = \mu \left(\frac{\mu(1-\mu)}{\sigma^2}-1 \right)

and

β=(1μ)(μ(1μ)σ21) \beta = (1 - \mu) \left(\frac{\mu(1-\mu)}{\sigma^2}-1 \right)

Examples

mom_beta(mean = .8, sd = .1) # The function is vectorized. mom_beta(mean = c(.6, .8), sd = c(.08, .1))