Is multi-method research more convincing than single-method research? An analysis of International Relations journal articles, 1980–2018

While some social scientists see multi-method research (MMR) as a promising strategy for strong causal inference, others argue that it does little to strengthen the validity of research. This paper offers a systematic review of how MMR has been used in mainstream International Relations (IR) and specifically in security studies. Using the TRIP Journal Article Database and Web of Science citation data, I examine whether MMR has reached its full potential. MMR has grown in prominence since the 2000s. Scholars use it most often to examine domestic rather than interstate issues. They cite MMR articles less than they cite quantitative single-method articles and about as often as they cite qualitative single-method research. This suggests that MMR is not more influential, nor perceived as more persuasive. However, this gap has decreased in recent years. The study provides insights into IR at the research design and disciplinary levels, the utility of MMR, and knowledge accumulation in social science.