Experimental research is characterized by:

• A. Manipulation of the independent variable, randomization, and a control group
• B. Absence of a control group
• C. Qualitative interviews only
• D. Observational correlation without manipulation

Answer: (A)

Experimental research relies on deliberately manipulating the independent variable and comparing outcomes between groups created by random assignment, including a control group that does not receive the experimental treatment. This combination helps establish cause-and-effect by isolating the impact of the manipulation from other factors. Randomization reduces preexisting differences between groups, and the control group provides a baseline for what would happen without the intervention. Without a control group, or without randomization, or without manipulation, strong causal conclusions aren’t possible.

The other options don’t fit because lacking a control group prevents a proper comparison to attribute changes to the intervention; qualitative interviews involve non-numeric data and don’t involve manipulating variables; and observing correlation without manipulation shows relationships but cannot establish causation.