Statistical approaches are subdivided into two major divisions, descriptive and inferential statistics. As the name implies, descriptive statistics entail describing, organizing, and summarizing information. Data are described by graphical methods, numerical indices, and tables. Descriptive statistics also often include a commentary discussing the data structure and any emergent patterns. In contrast, inferential statistics make inferences or estimations about a population from a sample through hypothesis testing and confidence intervals. Inferential statistics are associated with probability theory in order to reach conclusions about a variable beyond the data collected and determine the relative certainty of those conclusions. Statistical methodology, therefore, encompasses descriptive statistics that summarize data and inferential statistics that generalize data from a small group to a larger group. This entry focuses on descriptive statistics, ...