How do researchers determine what is true based on the data they collect? This question is one of the central concerns of statistics, which uses mathematical models to draw useful conclusions about the real world.

Italy, officially the Italian Republic, is a unitary parliamentary republic within the European Union, located in Southern Europe. To the north, it borders France, Switzerland, Austria, and Slovenia along the Alps.

The PhD is a doctoral degree, specifically called a "doctor of philosophy" degree. This is misleading because PhD holders are not necessarily philosophers (unless they earned their degree in philosophy!). That said, PhD recipients are able to engage in thought experiments, reason about problems, and solve problems in sophisticated ways.