The document discusses various quantitative research designs that can be used in studies, including experimental, quasi-experimental, and non-experimental designs. Experimental designs allow researchers to control variables and identify cause-and-effect relationships. Quasi-experimental designs are similar but do not involve random assignment. Non-experimental designs observe phenomena naturally without manipulation. Specific types of non-experimental or descriptive designs include surveys, correlational studies, ex-post facto studies, comparative studies, normative studies, evaluative studies, and methodological studies. Choosing an appropriate research design is important to effectively address the research problem and establish a framework for data collection and analysis.