lik_pois {ashr}R Documentation

Likelihood object for Poisson error distribution

Description

Creates a likelihood object for ash for use with Poisson error distribution

Usage

lik_pois(y, scale = 1, link = c("identity", "log"))

Arguments

y

Poisson observations.

scale

Scale factor for Poisson observations: y~Pois(scale*lambda).

link

Link function. The "identity" link directly puts unimodal prior on Poisson intensities lambda, and "log" link puts unimodal prior on log(lambda).

Details

Suppose we have Poisson observations y where y_i\sim Poisson(c_iλ_i). We either put an unimodal prior g on the (scaled) intensities λ_i\sim g (by specifying link="identity") or on the log intensities logit(λ_i)\sim g (by specifying link="log"). Either way, ASH with this Poisson likelihood function will compute the posterior mean of the intensities λ_i.

Examples

   beta = c(rnorm(100,50,5)) # prior mode: 50
   y = rpois(100,beta) # simulate Poisson observations
   ash(rep(0,length(y)),1,lik=lik_pois(y))


[Package ashr version 2.2-47 Index]