Manual muscle test grades are an example of which level of measurement?

Manual muscle test grades are an example of which level of measurement?

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

Answer: (C)

The main idea is that manual muscle test grades use an ordinal scale. You can rank someone's strength from none to normal, so higher grades reflect greater strength, but the intervals between grades aren’t uniform and you can’t derive exact differences or meaningful ratios from one grade to another. Therefore, it isn’t interval (which requires equal units) or ratio (which requires a true, meaningful zero and equal intervals). Nominal would ignore the ordered sense of strength, which isn’t the case here. So the grading is best described as ordinal.

The main idea is that manual muscle test grades use an ordinal scale. You can rank someone's strength from none to normal, so higher grades reflect greater strength, but the intervals between grades aren’t uniform and you can’t derive exact differences or meaningful ratios from one grade to another. Therefore, it isn’t interval (which requires equal units) or ratio (which requires a true, meaningful zero and equal intervals). Nominal would ignore the ordered sense of strength, which isn’t the case here. So the grading is best described as ordinal.