Evidence and outcomes: agendas, presuppositions and power.

This paper explores philosophical and methodological issues involved in determining 'What counts as making a meaningful difference?'--the fundamental question in health outcomes research and evidence-based practice. Eight diverse stakeholders are identified along with the competing agendas they bring to the debate. The power to define what counts as meaningful change in health status is typically rooted in disciplinary socialization, linguistic traditions and an orthodox consensus that circumscribes acceptable research foci and methods.