Question

The association between exposure to lead-based paint and mental deficits in children was studied, and the following information was recorded for each child in the study: race (Black or White), age (in years), and amount of exposure (rated from 0 for no exposure to 3 for more than three years’ exposure). Which of the following choices lists these variables in the order of nominal, ordinal, and interval/ratio?

Amount of exposure, race, age

Amount of exposure, age, race

Race, amount of exposure, age

None of the above

Answer 1

The association between exposure to lead-based paint and mental deficits in children was studied, and the following information was recorded for each child in the study: race (Black or White), age (in years), and amount of exposure (rated from 0 for no exposure to 3 for more than three years’ exposure). Which of the following choices lists these variables in the order of nominal, ordinal, and interval/ratio?

Solution:

Nominal variable is one which has two or more categories, but there is no intrinsic ordering to the categories.
Thus, form above data, race (Black or White) is nominal variable

An ordinal variable is similar to a nominal variable. The difference between the two is that there is a clear ordering of the variables.
Thus, amount of exposure (rated from 0 for no exposure to 3 for more than three years’ exposure) is ordinal variable

Intervals between the values of the interval variable are equally spaced (no such variable)
Age is not interval variable. But if we consider age range such as 0-5 years, 6-10 years then it can be considered as interval variable

Thus, correct response is Race, amount of exposure, age