Rwinsteps (version 1.0-1.1)

plot.ifile: Plotting Item Staistics

Description

These are Rasch model plot methods for item response functions, item inforamtion functions, item error functions, the test response function, the test information function, and the test error function, where each applies to an object of the corresponding class. plot.ifile summarizes the items within an ifile by plotting each of these functions in succession.

Usage

# S3 method for ifile
plot(x, theta = seq(-4, 4, length = 100),
  subset = 1:nrow(x), ...)
# S3 method for rirf
plot(x, theta = x$theta, add = FALSE,
  xlab = expression(theta), ylab = "P(X)", main = "IRF",
  lwd = 2, col = "r", ...)
# S3 method for riif
plot(x, theta = x$theta, add = FALSE,
  xlab = expression(theta), ylab = "Information", main = "IIF",
  lwd = 2, col = "r", ...)
# S3 method for rief
plot(x, theta = x$theta, add = FALSE,
  xlab = expression(theta), ylab = "Standard Error",
  main = "IEF", lwd = 2, col = "r", ...)
# S3 method for rtrf
plot(x, theta = x$theta, xlab = expression(theta),
  ylab = "Total", main = "TRF", lwd = 2, ...)
# S3 method for rtif
plot(x, theta = x$theta, xlab = expression(theta),
  ylab = "Information", main = "TIF", lwd = 2, ...)
# S3 method for rtef
plot(x, theta = x$theta, xlab = expression(theta),
  ylab = "Standard Error", main = "TEF", lwd = 2, ...)

Arguments

x

for plot.ifile, an object of class “ifile”, otherwise, either an ifile or a vector of item locations

theta

optional vector of theta values over which the functions will be evaluated

subset

an index vector indicating the items to plot, as row numbers or item names if present in the ifile

xlab

the x-axis label, as a string, defaulting to expression(theta)

ylab

the y-axis label, as a string, with default depending on the method

main

the plot title, with default depending on the method

lwd

line width, as an integer, defaulting to 2

col

vector of line colors, where the default "r" indicates a selection from the rainbow. Recycled if necessary

add

boolean, with default FALSE, indicating whether or not to add to the current plot

…

Further arguments passed to plot.default

See Also

ifile

Examples

# NOT RUN {
plot(ifile(-2:2))
# }