Which of the following is an example of an ordinal variable?

An ordinal variable is a type of categorical variable where the categories have a meaningful order or ranking, but the distances between the categories are not necessarily equal. Satisfaction ratings exemplify this perfectly, as they often reflect a range from low to high (for example, very dissatisfied, dissatisfied, neutral, satisfied, to very satisfied). These ratings establish a clear hierarchy that indicates greater or lesser satisfaction among respondents, although the actual differences in satisfaction levels between ratings are not quantifiable in precise numerical terms.

In contrast, other examples provided, such as eye color, political party, and zip code, are nominal variables. They categorize data without any inherent order. For instance, eye color does not suggest a greater or lesser value, political party affiliations are distinct categories without a ranking, and zip codes merely serve as identifiers for geographical areas without indicating any qualitative or quantitative measure. Hence, satisfaction ratings successfully represent an ordinal variable due to their ranked nature, making them suitable for this question.