Which statement describes an interval scale?

• A. It has a true zero point
• B. It has equal intervals between adjacent values but no true zero point
• C. It consists of qualitative categories
• D. It is defined by a ranked order of items

Answer: (B)

Interval scales are defined by equal intervals between adjacent values, which lets us meaningfully discuss differences. But they lack a true zero point, so we can’t talk about meaningful ratios. For example, Celsius temperatures have equal degree steps, and 20°C is 10°C higher than 10°C, but 20°C isn’t twice as hot as 10°C because zero °C doesn’t represent “no temperature.”

Having a true zero would describe a ratio scale, where ratios matter (one value can be meaningfully twice another). Qualitative categories describe a nominal scale, and a ranked order describes an ordinal scale.