plot.cat_output {irt}

Plot progress of a CAT algorithm for one examinee

Description

plot.cat_output Plots the progress of CAT for one examinee.

Usage

## S3 method for class 'cat_output'
plot(
  x,
  ...,
  plot_b = TRUE,
  se_band = TRUE,
  horizontal_line = "true_theta",
  title = "CAT Progress",
  suppress_plot = FALSE,
  base_r_graph = FALSE
)

Arguments

x

A "cat_output" object that is output of cat_sim function for one examinee.

...

Additional arguments.

plot_b

If TRUE, 'b' parameters of the administered items will be plotted along with intermediate theta estimates. The default value is TRUE.

se_band

A logical value. If TRUE, a standard error band is added around the estimated theta values. At each stage one standard error of that stage is added to and subtracted from the ability estimate at that stage. The default value is TRUE.

horizontal_line

An option to add a horizontal line. Provide either one of these or a list of a combination of these (except NULL).

"true_theta"

Add a horizontal line for true theta. Default option.

"final_theta"

Add a horizontal line at final theta (ability) estimate

NULL

No horizontal line added.

title

Title of the Plot

suppress_plot

If FALSE the function will print the plot. If TRUE, function will return the plot object. Default value is FALSE.

base_r_graph

Currently this function only works with package 'ggplot2'.

If TRUE function will plot graphs using base R graphics. If FALSE the function will check whether 'ggplot2' package is installed. If it is installed, it will use 'ggplot2' package for the plot. The default value is FALSE.

Value

Depending on the value of printPlot function either prints the CAT progress plot or returns the plot object.

Author(s)

Emre Gonulates

Examples

cd <- create_cat_design(ip = generate_ip(n = 100))
co <- cat_sim(true_ability = rnorm(1), cd = cd)

plot(co)

# Suppress item difficulties
plot(co, plot_b = FALSE)

# Suppress Standard Error Band
plot(co, se_band = FALSE)

# Add final theta estimate line
plot(co, horizontal_line = "final_theta")
plot(co, horizontal_line = "true_theta")

# Change Title
plot(co, title = "CAT Progress for Examinee ABC")

## Not run: 
# Change Text Size
plot(co) + theme(text=element_text(size=20))

# Change x-axis label
plot(co) + xlab("My New X Axis Label")

# Change y limits of the graph
plot(co) + coord_cartesian(ylim = c(-5,5))

# Change legend position
plot(co) + theme(legend.position="none")
plot(co) + theme(legend.position="left")

# Add a horizontal line
plot(co) + geom_hline(yintercept = -1, color = "red", linetype = 5)

## End(Not run)