irtplot: irtplot

In talbano/epmr: Tools for Educational and Psychological Measurement

irtplot

Description

Item Response Theory Plotting

Usage

ip_plot(
  x,
  theta,
  b,
  groups = rep(1, length(theta)),
  tests = rep(1, length(b)),
  type = "density"
)

irf_plot(x, ip = x$ip, theta = seq(-4, 4, length = 100))

tef_plot(x, ip = x$ip, theta = seq(-4, 4, length = 100))

Arguments

x	irtstudy output.
theta	vector of theta values, taken by default from x in ip_plot and in other functions defaulting to a sequence of values.
b	vector of item location parameters, taken by default from x.
groups	vector defining person groups, defaulting to one group.
tests	vector defining tests, i.e., item groups, defaulting to one.
type	type of plot generated by ip_plot, whether "density", the default, or "frequency", i.e., histogram.
ip	data frame of item parameters, taken from x.

Details

Functions for plotting results from item response theory models.

Examples

ritems <- c("r414q02", "r414q11", "r414q06", "r414q09",
  "r452q03", "r452q04", "r452q06", "r452q07", "r458q01",
  "r458q07", "r458q04")
rsitems <- paste0(ritems, "s")
pisagbr <- PISA09[PISA09$cnt == "GBR", rsitems]
irtgbr <- irtstudy(pisagbr)

# Item person map
print(ip_plot(irtgbr))

# Item response functions
print(irf_plot(irtgbr))

# Test response functions
print(tef_plot(irtgbr))

talbano/epmr documentation built on May 1, 2024, 11:10 a.m.