View source: R/distributions.R
mom_gamma | R Documentation |
Compute the shape and scale (or rate) parameters of the gamma distribution using method of moments for the random variable of interest.
mom_gamma(mean, sd, scale = TRUE)
mean |
Mean of the random variable. |
sd |
Standard deviation of the random variable. |
scale |
Logical. If TRUE (default), then the scale parameter is returned; otherwise, the rate parameter is returned. |
If \mu
is the mean and
\sigma
is the standard deviation of the random variable, then the method
of moments estimates of the parameters shape
= \alpha > 0
and
scale
= \theta > 0
are:
\theta = \frac{\sigma^2}{\mu}
and
\alpha = \frac{\mu}{\theta}
The inverse of the scale parameter, \beta = 1/\theta
, is the rate parameter.
If scale = TRUE
, then a list containing the parameters shape
and scale
; otherwise,
if scale = FALSE
, then a list containing the parameters shape
and rate
.
mom_gamma(mean = 10000, sd = 2000)
# The function is vectorized.
mom_gamma(mean = c(8000, 10000), sd = c(1500, 2000))
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.