How not to conduct a regression discontinuity design using a continuous measure of democracy

I review a recent article published in this journal (Ademi and Kimya, 2023) which uses a continuous measure of democracy as the basis for a ‘fuzzy regression discontinuity design’ investigating the effect of democratization on party system polarization. I argue that their design does not qualify as a regression discontinuity design because continuous measures of democracy produced by social scientists are not used to assign treatments to country-years, and because the authors misuse the auxiliary variable recording regime transitions used in their analysis.