Statistics is a branch of applied mathematics that deals with collecting, organising, analysing, reading and presenting data. Descriptive statistics make summaries of data. Inferential statistics makes predictions. Statistics helps in the study of many other fields, such as science, medicine, economics, psychology, politics and marketing. Someone who works in statistics is called a statistician. In addition to being the name of a field of study, the word "statistics" can also mean numbers that are used to describe data or relationships.