coin.spin: Function for Coin Spinning, Practical 11.1

In SMPracticals: Practicals for Use with Davison (2003) Statistical Models

Function for Coin Spinning, Practical 11.1

Description

This function computes the posterior distribution of the success probability theta when a coin is spun on its edge (or tossed), when the prior density for that probability is a mixture of beta densities.

Usage

coin.spin(para, r = 0, n = 0, n.points = 199)

Arguments

para	A matrix with 3 columns and k rows, where k is the number of components of the mixture. The first column contains the probabilities, and the next two the shape parameters a and b for the components.
r	Number of successes
n	Number of trials
n.points	The number of values of theta, equally-spaced between 0 and 1.

Details

This is provided simply so that readers spend less time typing. It is not intended to be robust and general code.

Value

x	Values of theta
y	Values of posterior density for theta

Author(s)

Anthony Davison ([e-mail])

References

Davison, A. C. (2003) Statistical Models. Cambridge University Press. Practical 11.1.

Examples

## From Practical 11.1:
para <- matrix( c(0.5, 10, 20, 0.5, 20, 10), nrow=2, ncol=3, byrow=TRUE)
prior <- coin.spin(para)
plot(prior, xlab="theta",ylab="PDF", type="l",ylim=c(0,6))
post <- coin.spin(para, r=4, n=10)

SMPracticals documentation built on May 29, 2024, 12:19 p.m.