This course provides an introduction to the principles and tools to retrieve, “tidy,” clean, and visualize data in preparation for statistical analysis. Principles of reproducibility and reusability are emphasized. It teaches techniques to wrangle and explore data. The emphasis is on preparation of data to ease the analysis rather than sophisticated analyses. Topics include methods to convert data from diverse sources into suitable form for data visualization and analysis; methods to scrape data from websites; data visualization; elementary database operations such as SQL’s join; construction of web-based analysis apps; and principles of reproducibility and reuseability, including literate programming, unit tests, and source code management.