Which type of data are measured on a scale with equal intervals and an arbitrary zero point, such that equal changes represent equal differences?

Which type of data are measured on a scale with equal intervals and an arbitrary zero point, such that equal changes represent equal differences?

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

Answer: (A)

Interval data are measured on a scale with equal intervals between adjacent values and an arbitrary zero point, so equal changes represent equal differences. Because the zero is not an absolute absence, you can add and subtract values meaningfully, but you cannot meaningfully talk about ratios. For example, Celsius temperature has equal intervals—going from 20 to 30 degrees is the same change as from 0 to 10 degrees—but 0 degrees does not mean “no temperature.” By contrast, scales with a true zero, like Kelvin temperature, allow meaningful ratios. Nominal data are just categories without inherent order, and ordinal data have order but unequal intervals; neither fits the idea of equal differences with an arbitrary zero.

Interval data are measured on a scale with equal intervals between adjacent values and an arbitrary zero point, so equal changes represent equal differences. Because the zero is not an absolute absence, you can add and subtract values meaningfully, but you cannot meaningfully talk about ratios. For example, Celsius temperature has equal intervals—going from 20 to 30 degrees is the same change as from 0 to 10 degrees—but 0 degrees does not mean “no temperature.” By contrast, scales with a true zero, like Kelvin temperature, allow meaningful ratios. Nominal data are just categories without inherent order, and ordinal data have order but unequal intervals; neither fits the idea of equal differences with an arbitrary zero.