For a beginner it becomes important to understand the various ways by which a variable could be measured and implications arising from it for the study. There are three perspectives that mutually not exclusive through which a variable could be classified:
- Causal relationship
- Design of the study
- Unit of measurement
Any concept that could be measured on scales like nominal, ordinal, interval and ratio is called a variable. Measurement scales leads to subjective responses, and also responses that could be measured with great precision for purposes of categorisation. The choice that a researcher could have on measuring a variable on a scale used for measurement depends upon the objective of the study and also the way the researchers want to convey their findings to the readers.