RBesT (version 1.8-1)

mixbeta: Beta Mixture Density

Description

The Beta mixture density and auxilary functions.

Usage

mixbeta(..., param = c("ab", "ms", "mn"))
ms2beta(m, s, drop = TRUE)
mn2beta(m, n, drop = TRUE)
# S3 method for betaMix
print(x, ...)
# S3 method for betaBinomialMix
print(x, ...)
# S3 method for betaMix
summary(object, probs = c(0.025, 0.5, 0.975), ...)
# S3 method for betaBinomialMix
summary(object, probs = c(0.025, 0.5, 0.975), ...)

Value

mixbeta returns a beta mixture with the specified mixture components. ms2beta and mn2beta return the equivalent natural a and b parametrization given parameters m, s, or n.

Arguments

...

List of mixture components.

param

Determines how the parameters in the list are interpreted. See details.

m

Vector of means of beta mixture components.

s

Vector of standard deviations of beta mixture components.

drop

Delete the dimensions of an array which have only one level.

n

Vector of number of observations.

x

The mixture to print

object

Beta mixture object.

probs

Quantiles reported by the summary function.

Details

Each entry in the ... argument list is expected to be a triplet of numbers which defines the weight $w_k$, first and second parameter of the mixture component $k$. A triplet can optionally be named which will be used appropriately.

The first and second parameter can be given in different parametrizations which is set by the param option:

ab

Natural parametrization of Beta density (a=shape1 and b=shape2). Default.

ms

Mean and standard deviation, $m=a/(a+b)$ and $s=\sqrt{\frac{m(1-m)}{1+n}}$, where $n=a+b$ is the number of observations. Note that $s$ must be less than $\sqrt{m(1-m)}$.

mn

Mean and number of observations, $n=a+b$.

See Also

Other mixdist: mix, mixcombine(), mixgamma(), mixmvnorm(), mixnorm(), mixplot

Examples

## a beta mixture
bm <- mixbeta(rob = c(0.2, 2, 10), inf = c(0.4, 10, 100), inf2 = c(0.4, 30, 80))

# mean/standard deviation parametrization
bm2 <- mixbeta(rob = c(0.2, 0.3, 0.2), inf = c(0.8, 0.4, 0.01), param = "ms")

# mean/observations parametrization
bm3 <- mixbeta(rob = c(0.2, 0.3, 5), inf = c(0.8, 0.4, 30), param = "mn")

# even mixed is possible
bm4 <- mixbeta(rob = c(0.2, mn2beta(0.3, 5)), inf = c(0.8, ms2beta(0.4, 0.1)))

# print methods are defined
bm4
print(bm4)