Which statement correctly describes experimental studies?

Which statement correctly describes experimental studies?

• A. They do not involve manipulating variables
• B. They test predictions by manipulating an independent variable
• C. They focus only on descriptive summaries
• D. They are never used to establish causality

Answer: (B)

Experiments are defined by actively changing something—an independent variable—and watching what happens to another factor, a dependent variable. This deliberate manipulation is what lets researchers infer causality, because they can compare outcomes under different conditions while holding other factors as constant as possible. A proper experimental design usually includes a control group or baseline condition and, ideally, random assignment to groups to minimize confounding influences. So, this statement is the best fit because it captures the core practice of experiments: predictions are tested by manipulating the independent variable and observing the resulting effects. In contrast, descriptions that claim experiments don’t manipulate variables describe observational or descriptive studies, which don’t establish cause-and-effect in the same way. And the idea that experiments can never establish causality is inaccurate because, when well-designed, they are specifically aimed at determining causal relationships.

Experiments are defined by actively changing something—an independent variable—and watching what happens to another factor, a dependent variable. This deliberate manipulation is what lets researchers infer causality, because they can compare outcomes under different conditions while holding other factors as constant as possible. A proper experimental design usually includes a control group or baseline condition and, ideally, random assignment to groups to minimize confounding influences.

So, this statement is the best fit because it captures the core practice of experiments: predictions are tested by manipulating the independent variable and observing the resulting effects. In contrast, descriptions that claim experiments don’t manipulate variables describe observational or descriptive studies, which don’t establish cause-and-effect in the same way. And the idea that experiments can never establish causality is inaccurate because, when well-designed, they are specifically aimed at determining causal relationships.