Scientific Justification

This paper is a strong candidate for replication because it addresses a theoretically and politically consequential question—whether conspiracy mentality is concentrated on the political right, at both ideological extremes, or among those out of power—using very large cross-national samples from 26 countries. The authors report both linear and quadratic associations, but they also emphasize that these effects are small and heterogeneous across countries. That combination of substantive importance, statistical complexity, and cross-national heterogeneity makes this an especially valuable target for replication. A successful replication would help clarify whether the observed non-linear pattern is robust across time, political contexts, measurement choices, and levels of political polarization. The paper is also highly visible and already substantially cited, increasing the value of independent confirmation.

Data Location

The article states that all data for Studies 1 and 2 are available on OSF: https://osf.io/jqnd6/ and that the supporting code is available there as R Markdown (or https://osf.io/jqnd6/overview).

Suggested Robustness Checks

- Test whether the linear and quadratic effects hold (whether conclusions are indeed warranted) - Test whether the linear and quadratic effects hold under different minor specifications - Test whether the linear and quadratic effects hold under alternative codings of ideology (e.g., raw self-placement, standardized within-country placement, categorical ideology bins). - Test the nomological network of ideological extremes - Examine sensitivity to exclusion of country samples with low ideological variance (or unusual party-system structures?). - Compare results using multilevel specifications with and without country-level moderators such as democratic quality, party-system fragmentation, or incumbent turnover. - Probe whether the “opposition party” effect is robust to alternative operationalizations of political control deprivation. - Test whether findings replicate with adjacent outcomes such as specific conspiracy beliefs, not just conspiracy mentality. - Suggested Deviations from Original Design

Suggested Deviations

A useful replication would extend the design temporally and politically by using post-2022 data, ideally from the same or overlapping countries, because conspiracy discourse and ideological alignment may have shifted after COVID, the Ukraine war, and more recent democratic backsliding. A particularly informative deviation would be to preregister a comparison between self-placement ideology, party preference, and issue-based ideology, because the ideological meaning of “left” and “right” varies considerably cross-nationally.