polyPlot: Plot Polytomous Item Response Theory models.

In ppanko/irtPlot: General IRT Plotting

Description

polyPlot returns a plot within a new device and saves to chosen directory.

Usage

polyPlot(dat, theta = seq(-3, 3, 0.01), title = NULL, ddir = getwd(),
  save = FALSE, model, type, fln = paste0(model, "_", type, "_",
  colnames(dat), ".jpg"), dpi = 300, height = 8.5, width = 10,
  itmNam = colnames(dat), silent = FALSE)

Arguments

dat	A data frame containing at least one item as a column.
theta	The ability parameter across which to plot response parameterization.
save	Whether or not the generated plots will be saved. Default is "FALSE"
model	The desired model to fit to the data.
type	The plot type to generate. See Details for a list of valid types.

Details

This function specializes in generating polytomous models and plot types. Namely, the models are "grm" and "pcm" and the possible types are "icc", "icf", and "crp".

Value

Prints the specified plot by default leaving the options to save to the user.

Examples

## Example notation:
library(ltm)
data <- Science[,c(1,3)]
colnames(data) <- paste0("Item ", 1:ncol(data))
polyPlot(data, theta, model = "grm", type = "crp")

ppanko/irtPlot documentation built on May 25, 2019, 11:24 a.m.