# 1.1.1 - Categorical & Quantitative Variables

1.1.1 - Categorical & Quantitative VariablesVariables can be classified as **categorical **or **quantitative**. Categorical variables are those that provide groupings that may have no logical order, or a logical order with inconsistent differences between groups (e.g., the difference between 1st place and 2 second place in a race is not equivalent to the difference between 3rd place and 4th place). Quantitative variables have numerical values with consistent intervals.

- Categorical variable
- Names or labels (i.e., categories) with no logical order or with a logical order but inconsistent differences between groups (e.g., rankings), also known as qualitative.

- Quantitative variable
- Numerical values with magnitudes that can be placed in a meaningful order with consistent intervals, also known as numerical.

## Example: Weight

A team of medical researchers weigh participants in kilograms. Weight in kilograms is a **quantitative ****variable **because it takes on numerical values with meaningful magnitudes and equal intervals.

## Example: Favorite Ice Cream Flavor

A teacher conducts a poll in her class. She asks her students if they would prefer chocolate, vanilla, or strawberry ice cream at their class party. Preferred ice cream flavor is a **categorical ****variable **because the different flavors are categories with no meaningful order of magnitudes.

## Example: Birth Location

A survey asks “On which continent were you born?” This is a **categorical ****variable **because the different continents represent categories without a meaningful order of magnitudes.

## Example: Children per Household

A census asks every household in a city how many children under the age of 18 reside there. Number of children in a household is a **quantitative ****variable **because it has a numerical value with a meaningful order and equal intervals.

## Example: Highway Mile Markers

When a car breaks down on the highway, the emergency dispatcher may ask for the nearest mile marker. Highway mile marker value is a **quantitative ****variable **because it is numeric with a meaningful order of magnitudes and equal intervals.

## Example: Running Distance

A runner records the distance he runs each day in miles. Distance in miles is a **quantitative ****variable **because it takes on numerical values with meaningful magnitudes and equal intervals.

## Example: Highest Level of Education

A census asks residents for the highest level of education they have obtained: less than high school, high school, 2-year degree, 4-year degree, master's degree, doctoral/professional degree. This is a **categorical variable**.** **While there is a meaningful order of educational attainment, the differences between each category are not consistent. For example, the difference between high school and 2-year degree is not the same as the difference between a master's degree and a doctoral/professional degree. Because there are not equal intervals, this variable cannot be classified as quantitative.

## Example: Online Courses Taught

A survey designed for online instructors asks, "How many online courses have you taught?" Three options are given: "none," "some," or "many." While there is a meaningful order of magnitudes, there are not equal intervals. This is a **categorical variable**.

If the survey had asked, "How many online courses have you taught? Enter a number." this would be a **quantitative variable**. Here, participants are answering with the number of online courses they have taught. This is a numerical value with a meaningful order of magnitudes and equal intervals.