An independent variable is the factor that is changed, controlled, or selected by a researcher to see how it affects another variable (the dependent variable) in a study or experiment.

What is an independent variable?

  • It is the cause or input in a cause‑and‑effect relationship.
  • Its value does not depend on other variables in the study, which is why it is called “independent.”
  • In a function like y=f(x)y=f(x)y=f(x), xxx is the independent variable and yyy is the dependent variable.

In experiments and research

  • The independent variable is what the researcher manipulates (for example: temperature, type of therapy, presence/absence of music while studying).
  • The dependent variable is what is measured as an outcome, such as plant growth, depression scores, or test performance.

Other names you might see

  • Explanatory variable or predictor variable in statistics and data analysis.
  • Input variable or regressor in mathematical modeling and regression.

Simple example

  • Study question: “Does temperature affect plant growth?”
    • Independent variable: temperature (for example, 15°C, 20°C, 25°C).
* Dependent variable: plant growth (for example, height in centimeters after 3 weeks).

Quick HTML table for clarity

html

<table>
  <thead>
    <tr>
      <th>Aspect</th>
      <th>Independent Variable</th>
      <th>Dependent Variable</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>Role</td>
      <td>Presumed cause/input[web:3][web:9]</td>
      <td>Observed effect/output[web:3][web:9]</td>
    </tr>
    <tr>
      <td>Researcher’s action</td>
      <td>Manipulated or controlled[web:3][web:9]</td>
      <td>Measured or recorded[web:3][web:9]</td>
    </tr>
    <tr>
      <td>Function notation</td>
      <td>x in y = f(x)[web:7]</td>
      <td>y in y = f(x)[web:7]</td>
    </tr>
    <tr>
      <td>Common synonyms</td>
      <td>Explanatory, predictor, input[web:3][web:5]</td>
      <td>Response, outcome[web:3][web:9]</td>
    </tr>
  </tbody>
</table>

Information gathered from public forums or data available on the internet and portrayed here.