plotCCC {conquestr}

plotCCC

Description

Creates a plot of an item characteristic curve (by response category). For a dichotomous item, this will yield a single curve, for polytomous items this will produce a curve for each response category. Note this is not for use with rout files. See the generic function plotRout for plotting rout files.

Usage

plotCCC(
  item,
  abilities,
  responses,
  weights = NULL,
  groups = NULL,
  range = c(-6, 6),
  by = 0.1,
  linetype = "bins",
  bins = 10,
  plotZero
)

Arguments

item

A matrix of item parameters for a single item. Matrix should be of the form used in simplef

abilities

A vector of doubles estimated person abilities.

responses

A vector of integers giving the observed person responses to this item.

weights

A vector of doubles of sampling weights.

groups

A factor vector indicating groups.

range

Lower and upper bounds to plot over (defaults to c(-6, 6)).

by

A double. The increment to the sequence along range used to plot the model lines.

linetype

A string. Should the empirical lines be based on "bins", or "regression". Defaults to "bins"

bins

If linetype is "bins", how many bins should be used to chunk the empirical lines? defaults to 10. Ignored otherwise.

plotZero

Should the zero category be plotted? Defaults to FALSE when item is dichotomous and TRUE otherwise.

Value

A ggplot2 object.

Examples

myRout <- ConQuestRout()
myPlot <- plotRout(myRout)
## Not run: 
# if you run the above example you will have an ICC plot in the object `myPlot`.
plot(myPlot)

## End(Not run)