Definitions. Statistics: A Branch of mathematics that involves techniques for dealing with sets of numbers:Summarizing themDescribing themFiguring out what they mean. Definitions. 2 types of statistics:Descriptive statistics: Used to describe and summarize (Example: The average height of people in this class is 5\'5\").Inferential statistics: Used to figure out what the numbers mean. More specifically, to make inferences from samples to populations..