Enhancing Cross-Cultural Comparisons in International Large-Scale Assessments: A Comprehensive Investigation and Guideline Development Using TIMSS 2019 and TALIS 2018 Data

library(rd3c3) is A wrapper function library designed to fit model-based invariance modelsand alignment methods to assess cross cultural comparability of responses between countries andgroups, on international large-scale assessments.It helps researchers to write Mplus code, via MplusAutomation to implement invariance analysis.It uses graded response models with a probit link (i.e., confirmatory factor analysis with ordinalindicators).

International tests that compare education systems across countries—such as PISA and TIMSS—play an important role in shaping education policy worldwide. They show how well different countries’ schools perform, help identify inequalities, and allow nations to measure themselves against international standards. This information can guide decisions about what is taught, how it is taught, and where resources should go, while encouraging continuous improvement.
However, making fair comparisons across cultures is difficult. Differences in language, school systems and cultural backgrounds can introduce bias. For the results to be trustworthy, the tests must measure the same things in the same way in every country. This is called measurement invariance. The strictest form required for reliable score comparisons is known as scalar invariance.
A newer statistical method called Alignment Optimisation offers a more flexible way to achieve this. It adjusts the test items so they align as closely as possible across countries while allowing for small differences. This can make cross-country comparisons fairer and more accurate.
The method is not yet straightforward to use. There are no widely agreed rules for applying it, especially when the number of questions or the size of the groups being compared varies. Its success can also depend on these practical details.
To develop clearer, more practical guidelines, researchers are examining questionnaires from major international studies, including TIMSS 2019 and TALIS 2018. By studying how people respond to these questions in different countries, they hope to understand the challenges better and produce reliable advice for future cross-cultural education research.