Final answer:
The variable that is not categorical among the given options is 'age of a person,' which is a numerical variable because it represents a measurable quantity that can be expressed in units of time, specifically years.
Step-by-step explanation:
The question you've asked is about identifying which one of the following variables is not categorical:
- Age of a person
- Gender of a person: male or female
- A choice on a test item: true or false
- Marital status of a person (single, married, divorced, other)
To address your question, let's first define what a categorical variable is. A categorical variable places individuals or items into categories, such as party affiliation (Republican, Democrat, Independent) or living arrangements (dormitory, apartment, with parents, other). On the other hand, a numerical variable takes on values that are numbers with meaningful magnitudes and can be subjected to arithmetic operations. Examples of numerical variables include weight in pounds and time in hours.
Given the options:
- Age of a person is a numerical variable because it represents a measurable quantity that can be expressed in units of years.
- Gender of a person is a categorical variable because it places people into categories without a numerical value.
- A choice on a test item is a categorical variable because it categorizes responses into 'true' or 'false' with no numerical meaning.
- Marital status is a categorical variable because it classifies a person's relationship status into categories such as single, married, divorced, or other.
Therefore, the variable that is not categorical is age of a person, which is a numerical variable.