1. The document outlines different types of research designs - descriptive studies that observe phenomena without manipulation, and experimental studies that intentionally introduce a treatment and observe the results.
2. Descriptive studies collect information to demonstrate relationships, while experimental studies test hypotheses by manipulating variables and using control groups.
3. Research design provides a framework and plan to address research questions while maintaining integrity, protecting subjects, and minimizing bias. The chosen design depends on the question, resources, and feasibility.