Variables are used in a literature review to help organize and categorize the different elements of previous literature. They are used to identify and analyze the key concepts, themes, or ideas that have been studied in previous research. By identifying and defining variables, researchers can establish a framework for understanding the existing body of literature and identify gaps or areas for further investigation. Variables can also be used to compare and contrast different studies, identify trends or patterns, and assess the overall body of evidence on a particular topic.
