What is the variable you hypothesize to affect or predict an outcome in a linear regression called?

The variable that is hypothesized to affect or predict an outcome in a linear regression is known as the independent variable. This term refers to the variable that is manipulated or altered in order to observe its effect on another variable, which is typically the outcome or response variable. In the context of linear regression, the independent variable is the predictor, and the relationship between the independent variable(s) and the dependent variable is examined to infer any potential effects or correlations.

In a regression analysis, the independent variable is essential for establishing the direction and strength of the relationship with the dependent variable, thus allowing researchers to make predictions about the dependent variable based on the values of the independent variable. This foundational concept is central to statistical modeling and understanding causal relationships within data sets.