Variables in research can be categorized based on their characteristics and the type of data they represent. The NOIR framework—Nominal, Ordinal, Interval, and Ratio—describes four levels of measurement.
Variable Types: NOIR
Nominal: No order or rank among values for the variable (e.g., eye colors - blue, hazel, green)
Ordinal: The possible values have a clear sequence or hierarchy (e.g., ratings on a scale - poor, fair, good, excellent)
Interval: Numerical data without a true zero (e.g., temperature in Celsius - 0°C does not mean no temperature)
Ratio: Numerical data with a true zero (e.g., age, Height from ground level)