When collecting data, what type of variable is defined as having two distinct categories?

A variable that is defined as having two distinct categories is referred to as a binary variable. This type of variable specifically represents two possible outcomes or states, such as yes/no, true/false, or success/failure. The binary nature means that the variable can only take on one of these two values at any given time, making it a fundamental component in various statistical analyses, especially in fields like healthcare where outcomes are often categorized in this manner.

While categorical variables encompass a broader range of types, including those with more than two categories, binary variables are a more specific subset of categorical variables. Nominal variables, like categorical variables, can also represent categories without a specific order, but a binary variable is distinct in strictly having only two categories. Continuous variables, on the other hand, can take on an infinite number of values within a given range and are not relevant to the definition of having two distinct categories.