Independent variable


noun, plural: independent variables

(1) The variable in a functional relation whose value is independent, or is not affected by other variables.

(2) The variable that is manipulated in an experiment.

(3) The factor that affects the value of variables dependent to it.


For example:

An experiment is designed to see if a newly developed drug is effective in treating patients with cough. Some of the patients were given the drug while others the placebo. To determine if the drug is effective, the recovery of patients taking the drug is monitored and compared against that of the patients taking the placebo. If the patients taking the drug are able to recover faster than the patients taking the placebo, it could mean that the drug is effective against cough. If patients taking the drug and the placebo have the same rate of recovery, the drug may not be an effective treatment for cough.

In this case, the independent variable is the treatment given to patients with cough (i.e. the drug or the placebo).


  • controlled variable
  • explanatory variable
  • exposure variable
  • input variable
  • manipulated variable
  • predictor variable
  • regressor

Compare: dependent variable

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