Plot method for wizirt objects

All plots in wizirt use ggplot2 as a backend. Type 'theta_diff' also uses gghalves. For the item-focused plots, the types can be included in the same string to overlay the plots (e.g. resid_trace). For large numbers of persons and/or items, you may want to consider limiting the number printed at a time on some plots.

# S3 method for wizirt
plot(
  wizirt_fit,
  type = "tinfo",
  items = NULL,
  persons = NULL,
  facets = TRUE,
  quads = 10,
  return_data = FALSE,
  pfa = NULL,
  ifa = NULL
)

Arguments

type

Character. Currently, can be 'obs', 'trace', 'info', 'resid', 'stand', 'tinfo', 'theta', 'diff', 'theta_diff', 'np_prf', 'ld', or 'ld_pairs'.
items

Which items to plot? Either a numeric vector of item positions in the column names of the data, or a vector of the item names to plot. If nothing is specifed all items will be plotted.
persons

Which persons to plot? Either a numeric vector of person positions in the row names of the data, or a vector of the person ids to plot. If nothing is specifed all persons will be plotted.
facets

Logical. Should the plots be faceted? Default is TRUE.
quads

Numeric. For plots using residuals (i.e. resid, stand). How many quantiles should the data be broken into?
return_data

Logical. Should the plot data be returned. If TRUE returns a list with the plot and the data.
pfa

An object from irt_person_fit(). If omitted, irt_person_fit() is called within the function with the default settings (only for np_prf)
ifa

An object from irt_item_fit(). If omitted, irt_item_fit() is called within the function with the default settings (only for tinfo)

Examples

data("responses")
my_model <- wizirt(data = responses[, -1])
plot(my_model, type = "tinfo")

plot(my_model, type = "theta")

plot(my_model, type = "diff")

plot(my_model, type = "theta_diff")

plot(my_model, type = "obs", items = 1:4)

plot(my_model, type = "trace", items = 1:4)

plot(my_model, type = "trace", items = 1:4, facets = FALSE)

plot(my_model, type = "resid", items = 1:4)

plot(my_model, type = "stand", items = 1:4)

plot(my_model, type = "info", items = 1:4)

plot(my_model, type = "resid_trace", items = 1:4)

plot(my_model, type = "np_prf", facets = T, persons = 1:4)

plot(my_model, type = "np_prf", facets = F)