Which interval-type scale has a meaningful proportion and usually an absolute zero?

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

Answer: (B)

In measurement, the ability to form meaningful ratios comes from having a true zero. A ratio scale has an absolute zero that represents the absence of the attribute, so you can say one value is twice another or six is three times as much as two. That’s what “meaningful proportion” refers to, and it also lets you perform multiplicative comparisons legitimately.

Interval scales share equal spacing but their zero is arbitrary (for example, 0°C doesn’t mean no temperature), so ratios aren’t meaningful there. Nominal scales are just categories without order or distance, and ordinal scales have order but not equal intervals. Therefore, the scale that supports meaningful proportions and an absolute zero is the ratio scale.