Components {demest} | R Documentation

## Specify priors for the components in a Mix prior.

### Description

In normal usage, it is better to accept the default prior for the components than to specify it explicitly. End users are therefore unlikely to need this function.

### Usage

    Components(scale = HalfT())

### Arguments

`scale` | An object of class `HalfT`.

### Details

A `Mix` prior treats an interaction as a mixture of normal distributions. The means for these normal distributions are formed by multiplying a component for each dimension other than the 'along' dimension (typically the time dimension). Each element of these components has a normal prior with mean 0 and standard deviation `scaleComponent`. The prior for `scaleComponent` can be set using the `scale` argument.

Let s be the standard deviation of data y, or of `log(y)` in the case of a Poisson model without exposure. Let m be the `mult` argument. Then the default value for scale parameter in the half-t distribution is

Model | Default
Poisson with exposure | m 0.5
Poisson without exposure | ms 0.5
binomial | m 0.5
normal | ms 0.5

### Value

An object of class `Components`.

### See Also

Mixture priors are specified using `Mix`. The weights in a mixture prior are specified using `Weights`.

### Examples

    Components()
    ## A tighter prior on 'scaleComponent'
    Components(scale = HalfT(scale = 0.25))

[Package demest version 0.0.0.3.1 Index]