1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
|
\encoding{UTF-8}
\name{plotPWmap}
\alias{plotPWmap}
\title{Pathway Map}
\description{
A Bond-and-Fox Pathway Map displays the location of each item or
each person against its infit t-statistic. Pathway maps are useful
for identifying misfitting items or misfitting persons. Items or
people should ideally have a infit t-statistic lying between about
-2 and +2, and these values are marked.
}
\usage{
plotPWmap(object, pmap = FALSE, imap=TRUE,
item.subset = "all", person.subset = "all",
mainitem = "Item Map", mainperson = "Person Map",
mainboth="Item/Person Map",
latdim = "Latent Dimension",
tlab = "Infit t statistic",
pp = NULL, cex.gen = 0.6, cex.pch=1,
person.pch = 1, item.pch = 16,
personCI = NULL, itemCI = NULL, horiz=FALSE)
}
\arguments{
\item{object}{Object of class \code{Rm} or \code{dRm}}
\item{pmap}{Plot a person map if \code{TRUE}; the default is
\code{FALSE}.}
\item{imap}{Plot an item map if \code{TRUE} (the default); do not plot
if \code{FALSE}. At least one of \code{pmap} and \code{imap} must
be \code{TRUE}.}
\item{item.subset}{Subset of items to be plotted for an item map.
Either a numeric vector indicating the item numbers or a character
vector indicating the item names. If \code{"all"}, all items are
plotted. The number of items to be plotted must be > 1.}
\item{person.subset}{Subset of persons to be plotted for a person map.
Either a numeric vector indicating the person numbers or a character
vector indicating the person names. If \code{"all"}, all persons are
plotted. The number of persons to be plotted must be > 1.}
\item{mainitem}{Main title of an item plot.}
\item{mainperson}{Main title of a person plot.}
\item{mainboth}{Main title of a person/item joint plot.}
\item{latdim}{Label of the y-axis, i.e., the latent dimension.}
\item{tlab}{Label of the x-axis, i.e., the t-statistic dimension.}
\item{pp}{If non-\code{NULL}, this contains the
\code{person.parameter} data of the data object, avoiding the
need to recalculate it.}
\item{cex.gen}{\code{cex} as a graphical parameter
specifies a numerical value giving the amount by which plotting
text and symbols should be magnified relative to the
default. Here \code{cex.gen} applies to all text labels. The
default is 0.6.}
\item{cex.pch}{applies to all plotting symbols. The
default is 1.}
\item{person.pch, item.pch}{Specifies the symbol used for plotting
person data and item data respectively; the defaults are 1 and 16
respectively. See \code{\link{points}} for more information
about \code{pch} values.}
\item{personCI, itemCI}{Plotting confidence intervals for the the
person abilities and item difficulties. If \code{personCI=NULL}
(the default) no confidence intervals are drawn for person
abilities. Otherwise, specifying \code{personCI} draws
approximate confidence intervals for each person's ability.
\code{personCI} must be specified as a list, and the optional
elements of this list are \code{gamma}, the confidence level,
\code{col}, colour, and \code{lty}, line type. If \code{personCI}
is specified as an empty list, or not all of the list items are
specified, the default values
\code{personCI=list(gamma=0.95,col="orange",lty="dotted")} will be
used.
The same goes for \code{itemCI}, except that the default settings
are \code{itemCI=list(gamma=0.95,col="red",lty="dotted")}.}
\item{horiz}{if \code{TRUE}, the plot is horizontal, i.e., the latent
dimension is on the x-axis. The default is \code{FALSE}.}
}
\details{
This code uses vertical(horizontal) error bars rather than circles or boxes to
indicate standard errors. It also offers the possibility of plotting
item or person data on its own; this can considerably simplify the
reading of the plots for large datasets.
}
%\value{}
\references{
Bond T.G., Fox C.M. (2007) \emph{Applying the Rasch Model: Fundamental Measurement in the Human Sciences} (2nd ed.) chapter 3, Lawrence Erlbaum Associates, Inc.
Linacre J.M., Wright B.D. (1994) Dichotomous Infit and Outfit Mean-Square Fit Statistics / Chi-Square Fit Statistics. \emph{Rasch Measurement Transactions} \bold{8:2} p. 350, \url{https://www.rasch.org/rmt/rmt82a.htm}
Linacre J.M. (2002) What do Infit and Outfit, Mean-square and Standardized mean? \emph{Rasch Measurement Transactions} \bold{16:2} p. 878, \url{https://www.rasch.org/rmt/rmt162f.htm}
Wright B.D., Masters G.N. (1990) Computation of OUTFIT and INFIT Statistics. \emph{Rasch Measurement Transactions} \bold{3:4} p. 84--85, \url{https://www.rasch.org/rmt/rmt34e.htm}
}
\author{Julian Gilbey}
%\note{}
%\seealso{}
\examples{
res <- PCM(pcmdat)
pparm <- person.parameter(res)
plotPWmap(res, pp = pparm)
plotPWmap(res, pp = pparm, pmap = TRUE)
}
\keyword{models}
|
