Variable

A variable is anything measured or manipulated in research that varies across cases: age, test scores, treatment condition, attitudes. Variables are classified by role, such as independent, dependent, or confounding, and by measurement level, such as nominal, ordinal, interval, or ratio. The measurement level determines which statistics are appropriate, since a category cannot be averaged the way a continuous score can.

For a thesis, listing every variable, its role, and how it is measured is one of the fastest ways to sharpen a methodology chapter. Ambiguity about variables is a common examiner complaint, because it makes analyses impossible to evaluate or replicate. A simple variable table, defined once and used consistently across chapters, keeps the research question, the instruments, and the statistical tests aligned.