Humans often behave in predictable ways. The challenge for social scientists is to uncover the patterns underlying that behavior. Social scientists do this by examining the relationships between variables. A communication variable is any observable, measurable, communication behavior, characteristic, or concept that can take on different values, intensities, or states. These variables are often studied in relationship to other communication variables or physiological, psychological, linguistic, relational, social, and cultural influences or consequences. This entry describes the kinds of relationships examined between those variables and the types of statistical tests used to analyze those relationships.