This chapter provides an overview of the empirically found patterns of cross‐national policy convergence. The central questions addressed are the following. First, are the environmental policies of the countries under study actually converging and, if so, to what extent? Second, what is the direction of policy convergence; i.e., does convergence coincide with an upward or downward shift of regulatory levels? Third, to what extent do our empirical findings vary across different policy dimensions (presence‐of‐policies, policy instruments and policy settings) and policy types (trade‐related versus non‐trade‐related policies, obligatory versus non‐obligatory policies)?
To answer these questions, we rely on aggregate data analysis to measure the degree and direction of convergence. This way, it is possible to highlight general convergence patterns for the countries and policies under study. In addition to the presentation of aggregate data, we illustrate different convergence patterns for individual policy items. The items reflect the different dimensions (policy presence, instruments and settings) and policy types under study.
For measuring the degree of convergence (i.e., the extent of changes in policy similarity over time), we use several concepts that are commonly applied in the literature (cf. Heichel, Pape and Sommerer 2005 and chapter 3 above). First, to analyse convergence with regard to the presence of policies and policy instruments, we rely on the concept of adoption rates. This approach, which is typically used in research on policy diffusion, gives us information on the spread of policies and instruments across countries.