icc {bggum}  R Documentation 
Plots item characteristic curves given alpha, delta, and tau parameters.
icc(a, d, t, from = 3, to = 3, by = 0.01, layout_matrix = 1, main_title = "Item Characteristic Curve", sub = "", color = "black", plot_responses = FALSE, thetas = NULL, responses = NULL, response_color = "#0000005f")
a 
A numeric vector of alpha parameters 
d 
A numeric vector of delta parameters 
t 
Either a list of numeric vectors for the tau parameters for each option, or a numeric vector if the IRF for only one item is desired – note the first element of each vector should be zero 
from 
A numeric vector of length one, the lowest theta value to estimate response probabilities for; default is 3 
to 
A numeric vector of length one, the highest theta value to estimate response probabilities for; default is 3 
by 
A numeric vector of length one giving the spacing between theta values; default is 0.01 
layout_matrix 
An integer matrix dictating the layout of the plot; the default is a onecolumn matrix with one element for each item 
main_title 
A character vector giving the plots' main titles; default is "Item Characteristic Curve". 
sub 
An optional character vector of subtitles for the resulting plots, to be pasted onto the main title (helpful for titling individual plots when plotting multiple items' ICCs). 
color 
The color to plot the ICC line in; default is "black" 
plot_responses 
A logical vector of length one specifying whether to draw points at the theta estimates of actual responses; default is FALSE 
thetas 
An optional vector of theta estimates for response drawing;
if 
responses 
An optional matrix or vector (if the ICC for only one item
is desired) of responses; if 
response_color 
The color to plot the response points when

## We'll simulate data to use for these examples: set.seed(123) sim_data < ggum_simulation(100, 10, 4) ## You can plot the ICC for one item: icc(sim_data$alpha[1], sim_data$delta[1], sim_data$tau[[1]]) ## Or multiple items: icc(sim_data$alpha[1:2], sim_data$delta[1:2], sim_data$tau[1:2], sub = 1:2) ## You can also plot the actual responses over the expected response line: icc(sim_data$alpha[1], sim_data$delta[1], sim_data$tau[[1]], plot_responses = TRUE, responses = sim_data$response_matrix[ , 1], thetas = sim_data$theta)