Construct Validity, Measurement Invariance, and Nomological Network of Conspiracy Mentality Questionnaire (CMQ)...

The Conspiracy Mentality Questionnaire (CMQ) is a generic conspiracy mentality questionnaire whose content is suitable for different linguistic and cultural contexts. However, it needs to demonstrate strong measurement properties across these contexts to be effective. This study aimed to explore the psychometric properties of the CMQ across four different languages: Serbian, Bulgarian, Greek, and English. Despite its widespread use, the CMQ lacks sufficient research on its psychometric properties, especially in terms of measurement invariance across different linguistic versions (apart from the parent study). Moreover, to the best of our knowledge, no study has investigated the equivalence of the CMQ across genders, even though it is used for gender comparisons. To address this gap, we analyzed data from 2,897 participants (76.1% female) aged 18-89. Confirmatory factor analysis supported the modified one-factor structure, with a correlated residual that was replicated/previously reported, across languages. Measurement invariance analysis confirmed metric invariance across languages and scalar invariance across genders. Scalar invariance was established across education for Serbian, Bulgarian, and, with some caution, Greek, while it was not a property of the English sample. The nomological network of the CMQ aligns with previous findings regarding the correlates of conspiracy mentality.