spfa (version 1.0)

plotitem.cont: Item level perspective plots or contour plots for spfa models

Description

For continuous response data use plotitem.cont whereas discrete response data use plotitem.disc. For joint continuous and discrete data, use plotgroup.

Usage

plotitem.cont(
  param,
  nquad = 21,
  npoints = 101,
  xlim = c(-2.5, 2.5),
  ylim = c(0, 1),
  normal = TRUE,
  FUN = NULL,
  plot = TRUE,
  type = "contour",
  ...
)
plotitem.disc(
  param,
  ncat,
  npoints = 101,
  xlim = c(-2.5, 2.5),
  normal = TRUE,
  FUN = NULL,
  plot = TRUE,
  col = 1:ncat,
  lty = rep(1, ncat),
  ...
)
plotgroup(
  param,
  nquad = 21,
  npoints = 101,
  lim = c(-2.5, 2.5),
  normal = TRUE,
  plot = TRUE,
  type = "contour",
  ...
)

Value

plots. Item level perspective and contour plot

Arguments

param

parameter vector estimated from spfa model

nquad

an integer value of number of quadrature points. Default is 21

npoints

an integer value of number of x and y levels in the plot

xlim

the x limits of the plot. Two numerical values indicating the lower and upper limits

ylim

the y limits of the plot. Two numerical values indicating the lower and upper limits of the density. Note y is rescaled to a uniform [0,1] distribution.

normal

a logical value TRUE or FALSE indicating which density is used to rescale y.

FUN

a user supplied function to rescale.

plot

a logical value TRUE or FALSE indicating whether the plot is visualized.

type

the type of plot to be visualized. The default is the contour plot contour. It can also be changed to "persp" indicating perspective plots.

...

additional arguments passed to contour and persp

ncat

an integer value indicating the number of categories for the discrete item.

col

color of the line.

lty

line type

lim

limit

See Also

contour and persp

Examples

# Contour plot of the first item 

plotitem.cont(spfa::spfa_example$par[[1]])