any measurable characteristic, attribute, or factor that can vary between individuals or situations in a study. Variables are what researchers observe, measure, or manipulate to answer research questions. They can take on different types of values — such as numbers, categories, or “yes/no” responses — and are essential for analyzing relationships, patterns, and effects in research.
Synonyms: Factor, Attribute
Example
In a study on the effectiveness of a new exercise program for knee pain:
The primary variable might be the change in pain score over 12 weeks.
Secondary variables could include improvement in walking distance and quality-of-life scores.
Demographic variables would record participant age and gender.
Confounding variables might include body mass index (BMI) or use of pain medication, which could influence outcomes.