Which scale has a true zero point enabling statements like 'twice as much'?

Which scale has a true zero point enabling statements like 'twice as much'?

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

Answer: (C)

The key idea is that only certain measurement scales allow meaningful ratios. A ratio scale has a true zero point, meaning zero really means “none,” so you can say one amount is twice another, half as much, etc. This lets you compare quantities proportionally—weight, height, duration, or income are good examples. In an interval scale, the zero point is arbitrary (like the Celsius temperature scale), so you can talk about differences (10 degrees hotter) but not about meaningful ratios (20 is not truly twice 10). Nominal scales have no inherent order or magnitude at all, and ordinal scales show order but not equal intervals, so neither supports meaningful ratios. Hence, only the ratio scale supports statements like “twice as much.”

The key idea is that only certain measurement scales allow meaningful ratios. A ratio scale has a true zero point, meaning zero really means “none,” so you can say one amount is twice another, half as much, etc. This lets you compare quantities proportionally—weight, height, duration, or income are good examples. In an interval scale, the zero point is arbitrary (like the Celsius temperature scale), so you can talk about differences (10 degrees hotter) but not about meaningful ratios (20 is not truly twice 10). Nominal scales have no inherent order or magnitude at all, and ordinal scales show order but not equal intervals, so neither supports meaningful ratios. Hence, only the ratio scale supports statements like “twice as much.”