plotCqHist {conquestr}

plotCqHist

Description

generates a plot from a history object. Use getCqHist to create a history object from an 'ACER ConQuest' system file.

Usage

plotCqHist(
  myHist,
  centre = TRUE,
  params = c("all"),
  legend = FALSE,
  plotProblems = NULL
)

Arguments

myHist

an R object created by the getCqHist function.

centre

a Boolean representing whether the iteration history should be mean centred (within parameter). This is helpful for plots that include all parameters to ensure the Y axis is sensible. Consider, for example, the readability of a plot with raw values of the Likelihood and item parameters on it.

params

A string of which params to plot. Must be one or more of "all", "Likelihood", "Beta", Variance", "Xsi", "Tau". Note the match when using "Beta", Variance", "Xsi", "Tau" is by regular expression, so "Xsi1" will plot item location parameter 1, 10-19, 100-199 and so on.

legend

Should a legend be plotted?

plotProblems

an optional list defining which potential problem parameters to plot.

• Iters: The first element of the list is an integer defining how many of the final iterations to consider (e.g., identify parameters that are moving the most over the final 20 iterations). if NA, the default is to consider the last 10% of iterations.

• Magnitude: The second element of the list is number indicating the magnitude of change over the last n iterations. if NA, and Type is "relative", defaults to 30 times the largest change at the final iteration. if NA, and Type is "absolute", defaults to 0.05 logits.

• Type: The third element of the list is a string, either "relative" or "absolute":

  • "relative" indicates that Magnitude is the multiple of the change between the final iteration and the second-to-last iteration that indicates a potential problem.

  • "absolute" indicates that Magnitude refers to change between the the final iteration and the value in Iters that indicates a potential problem.

Value

A ggplot2 object.

Examples

## Not run: 
myHistPlot <- plotCqHist(getCqHist(ConQuestSys()))

## End(Not run)