Description Usage Arguments Details Value References Examples
Evaluates the probability density function of the beta-negative-binomial (BNB) distribution with a mean parameter and two shape parameters.
1 |
x |
vector of quantiles. |
mu |
mean parameter. |
a |
1st shape parameter. |
b |
2nd shape parameter. |
log |
logical; if TRUE, density values p are given as log(p). |
The BNB distribution has density
f(x) = (Γ(μ + x) B(μ + a, x + b)) / (Gamma(μ) Gamma(x + 1) B(a, b)),
where μ is the mean parameter and a and b are the first and second shape parameter.
Numeric vector of density values.
Frühwirth-Schnatter, S., Malsiner-Walli, G., and Grün, B. (2020) Generalized mixtures of finite mixtures and telescoping sampling https://arxiv.org/abs/2005.09918
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 | ## Similar to other d+DISTRIBUTION_NAME functions such as dnorm, it
## evaluates the density of a distribution (in this case the BNB distri)
## at point x
##
## Let's try with the density of x = 1 for BNB(1,4,3)
x <- 1
dbnb(x, mu = 1, a = 4, b = 3)
## The primary use of this function is in the closures returned from
## fipp() or nCluststers() as a prior on K-1
pmf <- nClusters(Kplus = 1:15, N = 100, type = "static",
gamma = 1, maxK = 150)
## Now evaluate above when K-1 ~ BNB(1,4,3)
pmf(priorK = dbnb, priorKparams = list(mu = 1, a = 4, b = 3))
## Compare the result with the case when K-1 ~ Pois(1)
pmf(priorK = dpois, priorKparams = list(lambda = 1))
## Although both BNB(1,4,3) and Pois(1) have 1 as their mean, the former
## has a fatter rhs tail. We see that it is reflected in the induced prior
## on K+ as well
|
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.