get_gamma_params: Get parameters of Gamma distribution

In COVID-19-Mobility-Data-Network/mobility: Tools for Analyzing Human Mobility Data

Description

A function that finds the shape and rate parameters required by the Gamma distribution given the observed mean mu and standard deviation sigma of the response variable. Parameters are found numerically using a two-dimensional Nelder-Mead optimization algorithm.

Usage

get_gamma_params(mu, sigma)

Arguments

mu	the desired mean of the Gamma distribution
sigma	the desired standard deviation of the Gamma distribution

Value

a named numeric vector giving the shape and rate parameters of the Gamma distribution

Author(s)

John Giles

See Also

Other utility: get_admin_level(), get_beta_params(), get_pop_vec(), get_unique_coords(), get_unique_ids()

Examples

mu <- 2
sigma <- 0.5

prm <- get_gamma_params(mu, sigma)

prm[1]/prm[2] # mean
sqrt(prm[1]/(prm[2]^2)) # sd

curve(dgamma(x, prm[1], prm[2]), 0, 5, xlab='Response variable', ylab='Density')
abline(v=mu, lty=2, col='red')

COVID-19-Mobility-Data-Network/mobility documentation built on Nov. 22, 2021, 12:17 a.m.