Which of the following variables is measured on a ratio scale (has a true zero)?

• A. Height
• B. Gender
• C. Movie rating
• D. Temperature in Celsius

Answer: (A)

Ratio scales include numbers that have both equal intervals and a true zero point, so you can meaningfully say one amount is a multiple of another. Height fits this: zero height would mean there is no height at all, and you can compare magnitudes meaningfully (one person could be twice as tall as another). You can perform multiplications like “twice as tall,” which is what ratio data allow.

Gender is a categorical (nominal) variable, not numeric, so ratio comparisons don’t apply.

Movie rating is typically ordinal: you know which rating is higher, but the intervals between ratings aren’t guaranteed to be equal, and there isn’t a true zero that means “no rating.”

Temperature in Celsius has equal intervals, but zero does not represent the absence of temperature, and negative values are possible, so it lacks a true zero.