View source: R/distributions.R
mom_beta | R Documentation |
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)
mean |
Mean of the random variable. |
sd |
Standard deviation of the random variable. |
If \mu
is the mean and
\sigma
is the standard deviation of the random variable, then the method
of moments estimates of the parameters shape1
= \alpha > 0
and
shape2
= \beta > 0
are:
\alpha = \mu \left(\frac{\mu(1-\mu)}{\sigma^2}-1 \right)
and
\beta = (1 - \mu) \left(\frac{\mu(1-\mu)}{\sigma^2}-1 \right)
A list containing the parameters shape1
and shape2
.
mom_beta(mean = .8, sd = .1)
# The function is vectorized.
mom_beta(mean = c(.6, .8), sd = c(.08, .1))
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