Contrasting and combining the historical counterfactual method and the synthetic control method

Abstract In recent years, many efforts have been made to bring quantitative and qualitative methods into dialogue. This article also moves in that direction. However, in contrast to most works, the present attempt does not concern the large-N/small-N issue but focuses instead on the sole single case study framework. Within this framework, two counterfactual methods, the historical counterfactual method, the qualitative one, and the synthetic control method, the quantitative one, have gained great importance without however meeting. This paper aims to advance mixed-methods research by bridging the gap between these two approaches. More precisely, it has assessed whether these two methods can be used together to understand what would have happened in a single case Z in the absence of an event X. The case study of the impact of Thatcher’s election on the UK pension system is then presented as an example of the joint use of the two methods.