% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/plots.R
\name{plot_pcc}
\alias{plot_pcc}
\title{Plot a person characteristic curve}
\usage{
plot_pcc(fit, person, n_groups = 5, grid = seq(-5, 5, 0.05))
}
\arguments{
\item{fit}{A fitted object from \code{\link{rasch}}.}

\item{person}{Row number of the person, or an ID matching
\code{fit$person$id}.}

\item{n_groups}{Number of item-difficulty intervals for the observed
points (capped by the number of observed items).}

\item{grid}{Item-location grid over which to draw the curve.}
}
\value{
Called for its plotting side effect; invisibly \code{NULL}.
}
\description{
The person characteristic curve: the probability of success as a
function of item location at the person's estimated measure, with the
person's observed responses overlaid, grouped into item-difficulty
intervals (proportion of maximum score per interval). Erratic responding
(for example lucky guessing on hard items by a low-proficiency person)
shows as observed points far from the curve, complementing the person
fit residual.
}
\examples{
set.seed(1)
d <- seq(-2, 2, length.out = 12)
X <- matrix(rbinom(300 * 12, 1, plogis(outer(rnorm(300), d, "-"))), 300, 12)
colnames(X) <- paste0("I", 1:12)
plot_pcc(rasch(X), person = 1)
}
