Dependent and independent variables are terms used in mathematical modeling, statistical modeling, and experimental sciences. A variable is any characteristic that can take on different values, such as height, age, temperature, or test scores.
An independent variable is the variable that is manipulated or varied in an experimental study to explore its effects. It is called "independent" because it is not influenced by any other variables in the study. Some common independent variables are time, space, density, mass, fluid flow rate, and previous values of some observed value of interest. Independent variables are also called explanatory variables, predictor variables, or regressors.
A dependent variable, on the other hand, is the variable that changes as a result of the independent variable manipulation. It is the outcome that researchers are interested in measuring, and it "depends" on the independent variable. Dependent variables are studied under the supposition or demand that they depend, by some law or rule, on the values of other variables. Dependent variables are also called response variables, outcome variables, or left-hand-side variables.
In an experiment, any variable that can be attributed a value without attributing a value to any other variable is called an independent variable. Models and experiments test the effects that the independent variables have on the dependent variables. Sometimes, even if their influence is not of direct interest, independent variables may be included for other reasons, such as to account for their potential confounding effect.
To determine the dependent and independent variables in a study, one should look for the following characteristics or keywords:
Dependent variables:
- Depend on other variables
- Represent the outcome you want to measure
- Are often the focus of the research study
- Are sometimes called the "response," the "symptoms," or the "outcome"
Independent variables:
- Arent affected by any other variables that the study measures
- Explain an event or outcome
- Can be a "treatment," a "risk factor," an intervention, or a predictor
- Could be a natural difference
In summary, independent variables are the cause, while dependent variables are the effect in a causal research study.
