In the context of probability experiments, which of the following best describes an $independent$ variable?

• A. A variable that always remains constant throughout the experiment
• B. A variable that is measured as the outcome of an experiment
• C. A variable whose value is manipulated to observe its effect on another variable
• D. A variable that is dependent on the outcome of another variable

Answer: (C)

Verified step by step guidance

1. Understand the context of the problem: it is asking about the definition of an independent variable in probability experiments or statistical studies.
2. Recall that in experiments, variables are classified mainly as independent or dependent variables. The independent variable is the one that the experimenter changes or controls to see how it affects another variable.
3. The dependent variable, on the other hand, is the outcome or response that is measured to see the effect of changes in the independent variable.
4. Analyze each option given: the independent variable is not a constant (it changes), it is not the measured outcome (that's the dependent variable), and it is not dependent on another variable (that would be the dependent variable).
5. Conclude that the best description of an independent variable is: 'A variable whose value is manipulated to observe its effect on another variable.'