Which of the following is NOT a scale of measurement?
a. ordinal
b. nominal interval
d. categorical
The correct answer and explanation is:
The correct answer is d. categorical.
Explanation:
Scales of measurement are ways to classify and measure variables in statistics and research. The four primary scales are nominal, ordinal, interval, and ratio. Each scale has specific characteristics that determine the kind of data and the statistical operations that can be performed.
- Nominal scale is the simplest level of measurement. It categorizes data without any order or ranking. Examples include gender, blood type, or colors. Nominal data only allow counting how many times each category occurs.
- Ordinal scale not only categorizes but also ranks the data in a meaningful order. However, the intervals between the ranks are not necessarily equal. An example is a satisfaction rating such as poor, fair, good, and excellent. Although these categories are ordered, the difference between them cannot be precisely measured.
- Interval scale has ordered categories with equal intervals between values, but it lacks a true zero point. Temperature in Celsius or Fahrenheit is an example because zero does not mean the absence of temperature. This scale allows addition and subtraction but not multiplication or division.
- Ratio scale (not listed in the options) includes all features of the interval scale but has a true zero point, indicating the absence of the quantity measured. Examples are weight, height, or time. This scale supports all arithmetic operations.
The term categorical is not a formal scale of measurement but a broad term that refers to any data that can be divided into categories. Categorical data include nominal and ordinal data but do not specify order or interval properties by themselves. Therefore, “categorical” is a general description of types of data rather than a specific scale of measurement.
Because “categorical” is not a distinct scale of measurement on its own, it is the correct answer for the choice that is NOT a scale of measurement.