Measurement of bullying in the Progress in International Reading Literacy Study 2021 cohort: Evidence for model misspecification

We evaluated the use of the Rasch model in the scoring and scaling of the context questionnaire scales from the Progress in International Reading Literacy Study 2021 cohort. Focusing on the bullying scale of the Progress in International Reading Literacy Study, we contrasted polytomous item response theory models using free (two-parameter logistic modeling) and fixed (Rasch modeling) discrimination parameters. Our analyses included data from 354,074 students from 63 countries or entities. Across all countries and entities, the Rasch-based model significantly distorted levels of bullying. The rank ordering of countries was consistent between models in 32 of the cases (50.8%), while in other cases there were changes in rank of up to five places. This study provides a robust basis for evidence-based decisions on whether a country is lagging or exceeding the global norm in aberrant behaviors such as bullying.