Concept and measurement: Exploring foreign policy similarity

Objective This paper aims to evaluate existing measurements and propose new ones for foreign policy similarity in international politics, emphasizing the importance of measurement in social science. The indicators designed must align with theoretical concepts and data characteristics to ensure consistency and validity. Methods The paper meticulously examines the assumptions and calculation methods of existing indicators, such as the S‐score and tau‐b, to rigorously evaluate their alignment with theoretical concepts and data characteristics. It then proposes alternative measurements that can address these criteria. Results The new indicators introduced in this paper address the limitations of the existing measurements. While producing values similar to existing measurements, they maintain conceptual consistency and operational interpretability. Additionally, the paper presents a tau‐like indicator weighted by national capability, an aspect not feasible with the previous tau‐b, leading to new meaningful conclusions. Conclusions This paper emphasizes the importance of understanding measurements when creating or using them. A deep comprehension of similarity measures and the research topic facilitates more precise measurements, thereby enhancing research outcomes in international politics.