Replication Data for: How to Measure Interest Group Influence: Italy’s Professional Orders and Liberalization Policy.

The question of who wins or loses in the policy process lies at the heart of recent research into both interest groups and public policy. However, one of the most difficult challenges when empirically analysing interest groups consists in knowing exactly how to measure their influence: despite the fact that this question has been addressed by political scientists for decades, significant problems remain regarding both the conceptual definition and empirical measurement of influence. In order to develop a better understanding of interest group influence, I recommend as follows: (a) that such influence be conceptualized as a degree of preference attainment; (b) that the degree of generality of the concept be downgraded, by breaking it up on the basis of two fundamental dimensions: the lobbying direction (pro-status quo or anti-status quo) and the policy-making stage (agenda setting; decision making; implementation); (c) to proceed with a manual hand-coding in order to obtain a list of the policy issues around which interest groups lobby; (d) to resort to an expert survey in order to evaluate these issues. This methodological approach is used to empirically measure the influence that Italy’s professional orders had on the liberalization process championed by the second Prodi government in 2006