simCAT_DC: Simulated Single-Item Format CAT Data

In irtQ: Unidimensional Item Response Theory Modeling

Simulated Single-Item Format CAT Data

Description

A simulated dataset containing an item pool, sparse response data, and examinee ability estimates, designed for single-item computerized adaptive testing (CAT).

Usage

simCAT_DC

Format

A list of length three:

item.prm

A data frame in item metadata format containing 100 dichotomous items.

• Items 1-90: Generated and calibrated under the IRT 2PL model.

• Items 91-100: Generated under the IRT 3PL model but calibrated using the 2PL model.

res.dat

A matrix of item responses from 10,000 examinees (rows) to 100 items (columns). NA marks an item that was not administered to the examinee. The columns have no names; they follow the row order of item.prm, whose id values are V1 to V100.

score

A numeric vector of ability estimates for the 10,000 examinees.

Author(s)

Hwanggyu Lim [e-mail]

Examples

# structure of the data
str(simCAT_DC, max.level = 1)


# item fit of the first five items, using the ability estimates as scores
x <- simCAT_DC$item.prm[1:5, ]
data <- simCAT_DC$res.dat[, 1:5]
irtfit(
  x = x, score = simCAT_DC$score, data = data, group.method = "equal.freq",
  n.width = 10, loc.theta = "average", range.score = c(-4, 4), D = 1
)

irtQ documentation built on Oct. 5, 2026, 5:08 p.m.