Rev Language Reference

dnBeta - Beta Distribution

The Beta distribution is a flexible distribution that returns a number between 0 and 1, so it is often used as a distribution for probabilities themselves.

Usage

dnBeta(RealPos alpha, RealPos beta)

Arguments

alpha : RealPos (pass by const reference)
The alpha shape parameter.
beta : RealPos (pass by const reference)
The beta shape parameter.

Domain Type

Probability

Details

The Beta distribution takes two parameters, alpha and beta. It is equivalent to the uniform when alpha = beta = 1. The probability density function is f(x) = x^(alpha - 1) * (1 - x)^(beta - 1) * Gamma(alpha + beta) / (Gamma(alpha) * Gamma(beta)), where Gamma is the gamma function.

Example

p ~ dnBeta(1.0,1.0)
x ~ dnBernoulli(p)
x.clamp(1)
moves[1] = mvSlide(p, delta=0.1, weight=1.0)
monitors[1] = screenmonitor(printgen=1000, separator = "        ", x)
mymodel = model(p)
mymcmc = mcmc(mymodel, monitors, moves)
mymcmc.burnin(generations=20000,tuningInterval=100)
mymcmc.run(generations=200000)

See Also

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