Statistics is a branch of applied mathematics dealing with data collection, organization, analysis, interpretation and presentation. Descriptive statistics summarize data. Inferential statistics make 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" also refers to numbers that are used to describe data or relationships.