A measure of illegal drug use asks respondents to place themselves in one of the following categories: every week, two to three times a month, once a month, less than once a month, never. Which level of measurement is this? A measure of illegal drug use asks respondents to place themselves in one of the following categories: every week, two to three times a month, once a month, less than once a month, never. Which level of measurement is this? Nominal Dichotomous Interval/Ratio Ordinal