Statistics How To

Qualitative Variable (Categorical Variable): Definition and Examples

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Types of Variable > What is a Qualitative Variable?

Qualitative Variable: What is it?

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A qualitative variable, also called a categorical variable, are variables that are not numerical. It describes data that fits into categories. For example:

  • Eye colors (variables include: blue, green, brown, hazel).
  • States (variables include: Florida, New Jersey, Washington).
  • Dog breeds (variables include: Alaskan Malamute, German Shepherd, Siberian Husky, Shih tzu).

These are all qualitative variables as they have no natural order. On the other hand, quantitative variables have a value and they can be added, subtracted, divided or multiplied.

qualitative variable.

Breeds of dog are qualitative variables. How many dogs are quantitative variables.

Quantitative Variable Qualitative Variables
Fractions Cat breeds
Decimals Cities
Odd Numbers Fast Food Chains
Whole Numbers College Major
Irrational Numbers Fraternities
Ordered pairs (x,y) Hair Color
Negative Numbers Computer Brands
Map coordinates Beer breweries
Positive Numbers Pop music genre
Exponents Tribe

As a general rule, if you can apply some kind of math (like addition), it’s a quantitative variable. Otherwise, it’s qualitative. For example, you can’t add blue+green (unless you’re in an art class — even then you “mix” them, you don’t add them!).

Numbers are sometimes assigned to qualitative variables for data analysis, but they are still classified as qualitative variables despite the numerical classification. For example, a study may assign the number “1” to males and “2” to females.

Qualitative Variables and the Nominal Scale

Qualitative variables aren’t ordered on a numerical scale in statistics so they are assigned nominal scales. The word “nominal” means “name”, which is exactly what qualitative variables are. A nominal scale is a scale where no ordering is possible or implied (except for alphabetical ordering like New York, Washington, West Virginia or Chelsea, Edinburgh, London). In other words, the nominal scale is where data is assigned to a category.

More on quantitative variables.

See also: categorical variable.


