Independent Variable

The independent variable is the presumed cause or predictor in a study — the factor you manipulate in an experiment, or measure and use to explain variation in survey research. It is also called the predictor or, in structural models, the exogenous variable.

In experimental designs the researcher controls it directly by assigning participants to conditions, which is what licenses causal claims. In non-experimental designs it is simply measured as it naturally occurs, so any relationship found is an association until a stronger design is applied.

A model may contain several independent variables, and multiple regression estimates each one's effect while holding the others constant. Keep them conceptually distinct and check for multicollinearity, because predictors that overlap heavily produce unstable, uninterpretable coefficients.