Which scale cannot specify the magnitude of differences between values?

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

Answer: (B)

The main idea here is that talking about how big a difference is between values requires equal intervals on the scale. An ordinal scale only preserves order: you know which value is higher, but you don’t know how far apart the ranks are. The gaps between adjacent values aren’t defined or guaranteed to be equal, so the magnitude of differences can’t be specified. Interval and ratio scales have equal units between values, so you can quantify exact differences (and ratios, in the ratio case). Nominal scales don’t even provide a meaningful order or distance, so discussing differences in magnitude isn’t meaningful there.