Table 2 Inclusion and exclusion criteria

Published in English

Not published in English, or no English full text available

Conducted original/primary research

Commentary, editorial, policy submission, book report, annual report, political party platform or news article; presents model with no empirical data; referred to other studies without conducting original research

Focused on the practice of lobbying or the quantity of lobby firms and lobbyists. This included studies that:

 (1) Measured a lobbying activity undertaken to influence public servants (e.g., meetings, submissions, committee participation)

 (2) Measured lobbying expenses

 (3) Measured the population of lobby firms/lobbyists (e.g., registration counts)

Only examined mechanisms to address lobbying (e.g., disclosure requirements); only analysed the influence of lobbying (not the practice); only analysed strategies targeting the public (e.g., grassroots campaigns, community coalition building, direct mail services); only analysed media framing strategies; only measured the revolving door (movement between public and private sector); focused mainly on other political strategies, with lobbying only a minor component of the study (e.g., narrative analysis of tobacco industry political strategies)

Used publicly available and replicable data (including FOIs subsequently shared in public repositories)

Data sources not public or easily replicable (e.g., investigative journalism, interviews, surveys, participant observation)

Methods provide reasonable detail regarding data sources and steps taken to access, clean and analyse the data

Methods unexplained, or not described in reasonable detail to enable replication (e.g., “data analysed by author”)