Which scale allows arithmetic operations such as addition and subtraction between values?

• A. Interval
• B. Nominal
• C. Ordinal
• D. Qualitative

Answer: (A)

The main idea here is understanding which measurement scale allows arithmetic between values. An interval scale uses numeric values with equal spacing between them, so the difference between two values is meaningful and you can add or subtract values in a way that supports calculating things like averages or differences over time. The zero point on this scale is arbitrary, so while you can subtract to find how much one value differs from another and you can sum values to compute an average, you can’t meaningfully talk about ratios (twice as much) because zero doesn’t represent the absence of the quantity.

Nominal data are just categories with no real order, so you can’t subtract or meaningfully average them. Ordinal data have order but the intervals between steps aren’t necessarily equal, so subtraction isn’t reliable. Qualitative data aren’t numeric and don’t support arithmetic. So the interval scale is the one that permits arithmetic operations like addition and subtraction between values.