Which data type can have a true zero point?

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

Answer: (C)

Having a true zero point means the zero value represents complete absence of the attribute, and you can meaningfully compare magnitudes by ratios. This property belongs to ratio data. Because ratio data have an absolute zero and equal intervals, you can say things like one measurement is twice another or one value is zero and the other is nonzero. Examples include weight, height, and duration. Nominal data are just categories with no numeric meaning, ordinal data have order but not fixed intervals, and interval data have fixed intervals but an arbitrary zero (such as Celsius temperature), so ratios aren’t meaningful there. Thus, ratio data are the only type that can have a true zero point.