pscl (version 0.5)

tracex: Trace Plot of Legislators' Ideal Points.

Description

Produces a trace plot of the samples from the posterior density of legislators' ideal points.

Usage

tracex(object, legis=NULL, d=1, conf.int=0.95,
       showAll = FALSE, start=rownames(object$x)[1])

Arguments

object

an object of class ideal.

legis

a vector of either the names of legislators (or partial matches of the names as given in the dimnames of object$x.

d

numeric, either a scalar or a vector of length two, the dimension(s) to be traced.

conf.int

numeric, the level of the confidence interval on the posterior mean to be plotted.

showAll

logical, if TRUE and length(d)==2, display traces for all selected legislators' ideal points on the one plot.

start

numeric, integer, the number of the iteration with which to begin plotting and calculations.

Details

Produces a trace plot showing the history of the MCMC iterations for the ideal point of each of the legislators (partially) named in legis. For d=1, each trace plot includes a trace over iterations, the cumulative mean, a moving average, the MCMC-based estimate of the mean of the posterior, and a confidence interval (specified by conf.int) around the mean of the posterior (using the estimated quantiles) of the respective MCMC iterates). All of these values are calculated beginning with the iteration specified by start.

When d is a vector of length two, a 2-dimensional trace plot is displayed, with the d[1] dimension on the horizontal axis, and the d[2] dimension on the vertical axis.

See Also

ideal; pmatch for matching legislators' names.

Examples

data(s109)
## short run for demo purposes only
id1 <- ideal(s109,
             meanzero=TRUE,
             maxiter=500,burnin=100,thin=10)
tracex(id1,legis="KENNEDY")

## n.b., no such legislator has Horrendous Goblin
tracex(id1,legis=c("KENNEDY","BOXER","KYL","Horrendous Goblin"))

id2 <- ideal(s109,
             d=2,
             maxiter=5000,   ## short run, and unidentified!
             burnin=500,
             thin=50)
tracex(id2,d=1,legis=c("KENNEDY","BOXER","KYL","Horrendous Goblin"))
tracex(id2,d=2,legis=c("KENNEDY","BOXER","KYL","Horrendous Goblin"))
tracex(id2,d=1:2,
       legis=c("KENNEDY","BOXER","KYL","Horrendous Goblin"))

## partial matching
tracex(id2,d=1:2,
       legis=c("KENN","BOX","BID","SNO","SPEC","MCCA","KYL",
               "Horrendous Goblin"),
       showAll=TRUE)