This uncertainty is a particularly vexed issue in education because of the range of people who have a stake in education (including students, parents, teachers, employers and trade unions). Uncertainty about costs is problematic, because education infrastructure is large and involves multiple levels of government, each often trying to minimise or shift the costs of reform. Assessing the relative costs and benefits of reform in education is also difficult, because of the large number of intervening factors that can influence the nature, size and distribution of any improvements resulting from reform.