After having studied policy instruments either as a type of public intervention on the economy and society or individually, political scientists have turned to the analysis of their combinations in a given country or across countries. This turn towards mixes, ecologies, constellations and concatenations has spawned a range of questions, such as why do governments adopt one instrument before another, what are the accountability effects of different combinations, and what is the best approach to designing a policy mix? In this paper we review different analytical strategies. Specifically, we consider the following theoretical and empirical strategies: diffusion across time (either in a single country or as result of spatial inter-dependence), governing by instrumentations, and policy-mixes. We find that these lenses do not perform particularly well when it comes to explaining the causal effects of different ecologies. We know more about how mixes are adopted and their role in governance (that is, the configuration of tools as dependent variable) than about the effects of adopting one mix or another (the configuration as independent variable). Consequently, we turn to an approach we are piloting to explore the effects of combinations, based on the institutional grammar tool and in particular the analysis of rules in action situations. To anchor the discussion to a specific problem, we concentrate on the accountability effects of ecologies of regulatory policy instruments. We discuss how this approach leads to a template for data-collection on the ‘bunch of tools’ and show how the data can be used to trace the causal effects of ecologies of regulatory policy instruments on accountability.
