Belief system alignment and cross-sectoral advocacy efforts in policy debates

Political actors participate in policy debates as an advocacy strategy to influence political opponents and public opinion. They often engage in cross-sectoral advocacy by participating in multiple adjacent debates. To investigate what factors influence cross-sectoral advocacy in policy debates, we examined advocacy coalitions in two health policy debates in the UK - the regulation of sugar-sweetened beverages and alcoholic drinks. We predicted cross-sectoral advocacy efforts across 237 actors, such as health charities, manufacturers, or retailers, as a function of their belief system alignment relative to their advocacy coalition. In a methodological innovation, Bayesian item response models were applied to policy beliefs stated publicly by actors in eleven newspapers to measure the ideological positions of actors and beliefs relative to their advocacy coalition. Extreme belief alignment relative to one's coalition, a small spread of stated beliefs, and a strong engagement were found to explain cross-sectoral advocacy.