What additional information is obtained by measuring two individuals on an interval scale compared to an ordinal scale?

What additional information is obtained by measuring two individuals on an interval scale compared to an ordinal scale?

• A. Whether the measurements are the same or different
• B. The direction of the difference
• C. The size of the difference
• D. None of the above

Answer: (C)

The key idea is that interval scales have equal, meaningful intervals between adjacent values, so you can quantify how far apart two measurements are. When you compare two individuals on an interval scale, you can state the exact size of the difference (for example, one score is 10 points higher than the other). On an ordinal scale, you can tell which person is higher or whether they are tied, and you can see who is higher, but you cannot determine how large the gap is between their positions. That ability to measure the magnitude of the difference is the additional information provided by the interval scale.

The key idea is that interval scales have equal, meaningful intervals between adjacent values, so you can quantify how far apart two measurements are. When you compare two individuals on an interval scale, you can state the exact size of the difference (for example, one score is 10 points higher than the other). On an ordinal scale, you can tell which person is higher or whether they are tied, and you can see who is higher, but you cannot determine how large the gap is between their positions. That ability to measure the magnitude of the difference is the additional information provided by the interval scale.