tests/testthat/test_00_NBII.R

In Stan125/gamlss.dist: Distributions for Generalized Additive Models for Location Scale and Shape

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#######     gamlss.dist        #######
#######   Distribution tests   #######
## Negative binomial type 2: NBII() ##
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## Context
testthat::context("NBII")

## Seed
set.seed(228)

## Family
fam <- NBII()

## Random Values
n <- 1e6
mu <- 1 
sigma <- 1
rvec <- rNBII(n, mu, sigma) 

## Empirical Moments
ex_emp <- mean(rvec)
vx_emp <- var(rvec)

## Theoretical moments
ex_theo <- fam$mean(mu, sigma)
vx_theo <- fam$variance(mu, sigma)

## Test here if they are about the same
expect_true(abs(ex_emp - ex_theo) < 0.02)  
expect_true(abs(vx_emp - vx_theo) < 0.02)