What Is a Nominal Variable?

Gender is a nominal variable.
••• couple fight image by Allen Penton from Fotolia.com

When you fill out a survey, your responses are often aggregated and subjected to statistical analysis. Nominal variables are often gathered in order to place people into groups. Thus, nominal variables are also called categorical variables.


According to researchers at University of California, Los Angeles, nominal variables contain two or more categories without a natural ordering of the categories. They essentially label data collected in a study.


University of Delaware professor Dr. John H. McDonald notes that an individual nominal variable is usually a name, not a number.


McDonald mentions a common nominal variable--gender (male or female). Other examples include political affiliation, hair color and beverage preference.


Nominal variables are often described in terms of percentages or proportions, writes McDonald. For instance, when you hear a statistic that 42 percent of respondents were male and 58 percent were female, the tally of the nominal variable "gender" is being reported.


It is common for researchers to convert measurement variables into a nominal variable for analytical purposes. McDonald uses an example of grouping people into a "low" and "high” cholesterol group based on their numerical cholesterol levels, which is a measurement variable. A cutoff point is established; everyone below that figure falls into the low group, and everyone above goes in the high group.

Related Articles

Can You Use a T-Test on Ranked Data?
How to Calculate Statistical Difference
How to Calculate Mode in Minitab
The Advantages of a Large Sample Size
What Are the Advantages & Disadvantages of Using Ordinal...
How to Approximate the Mean of Group Data
How to Calculate a T-Score
The Disadvantages of Linear Regression
How to Report Z-Score Results
What Are Parametric and Nonparametric Tests?
What Is the Meaning of Sample Size?
How to Calculate Unexplained Variance
Differences Between Conceptual Independent Variables...
The Difference Between Qualitative & Quantitative Traits...
What Is the Purpose of Factor Analysis?
How to Calculate Percentiles
The Definition of an Uncontrolled Variable
How to Chi-Square Test
How to Interpret an Independent T Test in SPSS
Statistical Analysis Tools