Which of the following is an example of an independent variable?

• A. Time spent on TikTok per day.
• B. Self-reported attention in class.
• C. GPA.
• D. Academic major.

Answer: (A)

The key idea is that the independent variable is the factor you actively change to see its effect on another outcome. Time spent on TikTok per day is the clearest example because you can vary how much someone uses TikTok and then observe how that change influences something like attention in class or GPA. The other options describe outcomes or inherent characteristics: attention in class is something you measure as a result, not something you manipulate; GPA is another outcome that results from many factors; academic major is a pre-existing attribute of a person and isn’t typically the input you change in a simple experiment. So, time spent on TikTok per day best fits the role of the independent variable.