Answer: Nominal
Explanation:
The level of measurement for the data given above is nominal, this is because color of hair are classed into categories : 1 for brown hair, 2 for blond hair, 3 for black hair and 4 for anything else. Hence, the figures assigned to the hair color specified above are only meant to categorize the different hair color into distinct categories.
Hence, the numeric values attached are not meant to give numerical meaning to the data. Hence, generating a mean or average value for the data does make computational sense and is hence invalid.