Which of the following is an example of the independent variable in a clinical trial?

• A. The treatment administered to patients
• B. Patient age
• C. Study funding source
• D. Outcome measure like ROM

Answer: (A)

In a clinical trial, the independent variable is what the researchers actively manipulate to see its effect. The treatment given to patients is the intervention they change or assign different groups to receive, so it represents the independent variable. The outcome measure, like range of motion, is what’s observed to determine the effect of that intervention, making it the dependent variable. Participant characteristics such as age are baseline factors that might influence results but aren’t the manipulated factor, and the funding source reflects sponsorship rather than the experimental manipulation. Therefore, the treatment administered is the independent variable.