The document discusses different types of research designs used in conducting research studies. It begins by defining research design and its purpose, which is to obtain answers to research questions and minimize variance. The key types of research designs covered are experimental, quasi-experimental, descriptive, and correlational designs. Experimental design aims to test causal relationships through manipulation of independent variables. Descriptive design observes and measures variables without manipulation to understand characteristics and trends. Correlational design examines relationships between non-manipulated variables. The document provides examples and comparisons of when each design is most applicable.