This document provides information about statistics and how Dr. John Snow used statistics to identify the source of a cholera outbreak in London in 1840. It explains how Snow mapped deaths from cholera and found they were concentrated around a single water pump, showing the pump was contaminating the water and causing deaths. His use of statistics led to identifying the source of the outbreak and changes that saved thousands of lives. The document then provides definitions and examples of key statistical concepts like mean, median, mode, and frequency tables.