Nerve conduction velocity is an example of which scale?

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

Answer: (C)

Scale types describe how measurements can be interpreted. Nerve conduction velocity has a true zero and equal intervals between values, so you can meaningfully say one value is twice another. Zero velocity literally means no conduction, and multiplying or forming ratios between speeds makes sense for this quantity. That combination—equal intervals plus a true zero—defines a ratio scale.

This differs from nominal data, which are just categories without order; from ordinal data, which have order but not equal spacing; and from interval data, which have equal spacing but no true zero (like temperature in Celsius).