Vignettes

These vignettes show how to work with IRW data for common psychometric tasks.

R

Each of these vignettes uses the irw R package to fetch data and walks through a complete analysis.

R
Calculating IMV Values
How much does a 2PL improve on a 1PL for a given dataset?

irw mirt imv

R
Simulating Item Difficulties
How can I simulate item difficulties that reflect real-world distributions rather than idealized assumptions?

irw

R
2PL Parameters Across Datasets
What do discrimination parameters look like across many cognitive/educational datasets in the wild?

irw mirt ggplot2

R
Conducting CFA with IRW Data
How do I fit a multi-factor CFA model to an IRW personality dataset?

irw lavaan psych

R
Item Text and Difficulty
Can simple linguistic features of item wording predict proportion correct across cognitive datasets?

irw ggplot2

R
The Dutch Identity
What does Holland’s (1990) Dutch Identity reveal about the structure of IRT models — and does it hold in real data?

irw mirt imv ggplot2

R
Response Time and Accuracy: An IMV Analysis
How much does knowing how fast a person responded improve predictions of whether they answered correctly, over and above IRT ability estimates?

irw mirt imv splines

Python

These vignettes use the irw Python package to fetch data.

Python
IRT Models in Python
How do I fetch IRW data in Python and fit 1PL, 2PL, 3PL, and graded response models?

irw mirt girth