pscl (version 1.5.5)

plot.predict.ideal: plot methods for predictions from ideal objects

Description

Plot classification success rates by legislators, or by roll calls, using predictions from ideal.

Usage

# S3 method for predict.ideal
plot(x, type = c("legis", "votes"),...)

Value

After drawing plots on the current device, exits silently returning invisible(NULL).

Arguments

x

an object of class predict.ideal.

type

string; one of legis or votes.

...

further arguments passed to or from other methods.

Author

Simon Jackman

Details

type="legis" produces a plot of the “percent correctly predicted” for each legislator/subject (using the classification threshold set in predict.ideal) against the estimated ideal point of each legislator/subject (the estimated mean of the posterior density of the ideal point), dimension at a time. If the legislators' party affiliations are available in the rollcall object that was passed to ideal, then legislators from the same party are plotted with a unique color.

type="votes" produces a plot of classification rates for each roll call, by the percentage of legislators voting for the losing side. The x-ordinate is jittered for clarity.

See Also

predict.ideal ideal

Examples

data(s109)
f = system.file("extdata","id1.rda",package="pscl")
load(f)
phat <- predict(id1)
plot(phat,type="legis")
plot(phat,type="votes")