Selectivity in research refers to the ability to specifically target and manipulate certain aspects or variables within a study, while excluding or controlling for others. This can involve selecting specific participants, materials, or methods that are relevant to the research question or hypothesis, in order to improve the validity and reliability of the study's results. Selectivity is important in research to ensure that the findings are accurate and meaningful, and to reduce potential bias or confounding factors that could impact the results. Researchers often use selectivity to focus on the most important or relevant aspects of their research, while minimizing distractions or irrelevant information.