Political scientists study matters concerning the allocation and transfer of power in decision making, the roles and systems of governance including governments and international organizations, political behaviour and public policies. They measure the success of governance and specific policies by examining many factors, including stability, justice, material wealth, peace and public health. Some political scientists seek to advance positive (attempt to describe how things are, as opposed to how they should be) theses by analyzing politics. Others advance normative theses, by making specific policy recommendations.