Which statement describes a ratio variable?

Which statement describes a ratio variable?

• A. an interval variable with meaningful ratios; e.g., a rating scale where 4 is twice 2.
• B. a nominal variable coded with integers.
• C. an ordinal variable where only order matters.
• D. a continuous variable with a natural zero that allows meaningful ratios.

Answer: (A)

Ratio variables are defined by having a true zero point and equal intervals, which lets you compare amounts and form meaningful ratios. The statement that best describes this is the one that calls the variable a continuous measure with a natural zero, enabling meaningful ratios. A true zero means “none of the quantity,” so you can say that something is twice as much as another only when zero represents the absence of the quantity (for example, height in centimeters, weight, distance, or Kelvin temperature). The other description falls short because an interval scale has equal intervals but an arbitrary zero, so ratios aren’t meaningful (for instance, saying 4 is twice 2 on a rating scale isn’t appropriate). Nominal and ordinal types don’t support arithmetic ratios at all.

Ratio variables are defined by having a true zero point and equal intervals, which lets you compare amounts and form meaningful ratios. The statement that best describes this is the one that calls the variable a continuous measure with a natural zero, enabling meaningful ratios. A true zero means “none of the quantity,” so you can say that something is twice as much as another only when zero represents the absence of the quantity (for example, height in centimeters, weight, distance, or Kelvin temperature).

The other description falls short because an interval scale has equal intervals but an arbitrary zero, so ratios aren’t meaningful (for instance, saying 4 is twice 2 on a rating scale isn’t appropriate). Nominal and ordinal types don’t support arithmetic ratios at all.