Nominal variables are variables that represent categories without any inherent order or ranking. They are simply used to distinguish different groups or categories without assigning any form of hierarchy or sequence to them (Babbie et al., 2007).
“Gender”, “marital status”, “nationality”, and “types of occupation” are typical nominal variables examples. These sorts of variables are commonly used in cross-sectional studies such as a population census. The critical distinction of nominal variables lies in their categorical nature and absence of systemic order (Katz, 2006b; Stockemer, 2018).
An Academic Definition: “A nominal variable consists of named categories, with no implied order among the categories.” (source: Norman & Streiner, 2008, p. 4)Nominal Variables Examples
1. Gender
Gender, with categories typically including “male”, “female”, and “other”, is a primary example of a nominal variable. Unlike ordinal variables, these categories have no presumed order or ranking.
2. Marital Status
Marital Status is a kind of nominal variable. The categories might be “single”, “married”, “divorced”, and “widowed”. No inherent hierarchy exists among these categories.
3. Nationality
Nationality is a nominal variable. For instance, labels like “American”, “Canadian”, “Chinese”, and “Brazilian” are chiefly identifiers, and don’t denote any order.
4. Hair Color
Hair color is another example of a nominal variable. Labels such as “black”, “brown”, “blonde” and “red” simply distinguish different hair color categories without implying any ranking or order.
5. Types of Pets
One could amass nominal data by asking about a person’s pet type – “dog”, “cat”, “fish”, “bird”, etc. These categories bear no logical order.
6. Car Brands
Car brands like “Toyota”, “Ford”, “Mercedes”, and “BMW” constitute another instance of a nominal variable. The names represent different brands without any inherent ranking or sequence.
7. Religion
Religion is a nominal variable. Categories might include “Christianity”, “Islam”, “Hinduism”, “Buddhism”, and “Atheism”. Each label simply identifies a specific religious group, with no rank order implied.
8. Disciplines of Study
The various disciplines of study — “Arts”, “Sciences”, “Commerce”, “Engineering” — are examples of nominal variables. These categories serve to label distinct branches of study, without any rank order.
9. Types of Houses
The kinds of dwelling places – “apartment”, “bungalow”, “condo”, “duplex” – can be classified as a nominal variable.
10. Language
Language is another nominal variable example. Categories such as “English”, “Spanish”, “French”, etc., are simply distinct labels without inherent hierarchy.
11. Blood Type
Classification by blood type (A, B, AB, O) represents a nominal variable.
12. Occupations
“Doctor”, “Engineer”, “Teacher”, “Artist” are types of occupations, hence a nominal variable, as there’s no inherent ranking or sequence among these professions.
13. Fast Food Chains
Fast food chains like “McDonald’s”, “Burger King”, or “KFC” come under nominal variables.
14. Music Genre
Music genres, such as “rock”, “jazz”, “classical”, “pop”, are examples of nominal variables. Here, the categories simply identify distinct types of music, with no rank order implied.
15. Eye Color
Eye color, categorized as “black”, “blue”, “hazel”, “green”, is another example of a nominal variable.
16. Favorite Sport
“Football”, “Basketball”, “Tennis”, “Cricket” are different sports, categorized as a nominal variable.
17. TV Show Genres
Genres of TV shows, such as “comedy”, “drama”, “reality”, and “sitcom” classify as nominal variables.
18. Postal Codes
Postal codes regularly classify as nominal variables. While they may contain numbers, the values don’t imply a specific order or ranking.
19. Patterns of Fabric
References to “striped”, “floral”, “polka dot”, or “solid color” are nominal variables, used to classify different fabric patterns. These categories have no inherent order or ranking.
20. Types of Computers
Categories such as “desktop”, “laptop”, and “tablet” can be classified as a nominal variable.
21. Types of Plants
“Bushes”, “trees”, “flowers”, and “grasses” are different types of plants and a great example of a nominal variable.
22. Political Affiliations
“Republican”, “Democrat”, “Independent”, and others are political affiliations. They classify as a nominal variable, as there’s no inherent ranking or sequence between them.
23. Patterns of Fabric
References to “striped”, “floral”, “polka dot”, or “solid color” are nominal variables, used to classify different fabric patterns. These categories have no inherent order or ranking.
24. Forms of Payment
Options like “credit card”, “debit card”, “cash”, or “cheque” are categorized as nominal variables.
25. Area of Residence
The section of a city someone might live in, such as “North”, “South”, “East”, or “West”, serves as a nominal variable. These categories merely function as distinct identifiers, not suggesting any hierarchy or sequence.
Types of Variables (Compare and Contrast)
Nominal variables typically contrast with other types of variables including ordinal, interval, and ratio variables.
Here’s a short overview.
- Ordinal variables have categories that can be logically ordered or ranked. While ordinal variables provide a sense of order or ranking, the exact or consistent distance between different categories remains unknown or inconsistent. For instance, t-shirt sizes (“small”, “medium”, “large”) that presents an order but doesn’t clarify the actual extent of the difference between the categories (Katz, 2006a; Katz, 2006b).
- Interval variables, in contrast to nominal variables, have ordered categories with known and consistent distances. Temperature measurements such as Celsius or Fahrenheit are the classic examples of interval variables (Lewis-Beck, Bryman & Liao, 2004).
- Ratio variables resemble interval variables, but with a defined zero point. For instance, weight measurements (grams, kilograms) are examples of ratio variables (Katz, 2006a; Katz, 2006b).
- Nominal variables are variables with categories that don’t have a natural order or ranking (Wilson & Joye, 2016). Unlike ordinal and interval variables, nominal variables do not provide any sense of hierarchy or order among the variables.
Conclusion
Nominal variables serve an essential role in different types of academic research as a form of categorical data. They enable differentiating data into distinctive groups or labels with no order or sequence. While these variables provide clear distinctions between categories, the lack of any order often limits the kind of statistical tests that can be applied to them. Their propensity to identify and differentiate rather than measure places nominal variables as a common choice for demographical data and other forms of categorical information.
References
Babbie, E., Halley, F., & Zaino, J. (2007). Adventures in Social Research: Data Analysis Using SPSS 14.0 and 15.0 for Windows (6th ed.). New York: SAGE Publications.
De Vaus, D. A. (2001). Research Design in Social Research. New York: SAGE Publications.
Katz, M. (2006). Study Design and Statistical Analysis: A Practical Guide for Clinicians. Cambridge: Cambridge University Press.
Katz, M. H. (2006). Multivariable analysis: A practical guide for clinicians. Cambridge: Cambridge University Press.
Lewis-Beck, M., Bryman, A. E., & Liao, T. F. (Eds.). (2004). The SAGE Encyclopedia of Social Science Research Methods (Vol. 1). London: SAGE Publications.
Norman, G. R., & Streiner, D. L. (2008). Biostatistics: The Bare Essentials. New York: B.C. Decker.
Stockemer, D. (2018). Quantitative Methods for the Social Sciences: A Practical Introduction with Examples in SPSS and Stata. London: Springer International Publishing.
Wilson, J. H., & Joye, S. W. (2016). Research Methods and Statistics: An Integrated Approach. New York: SAGE Publications.
Dr. Chris Drew is the founder of the Helpful Professor. He holds a PhD in education and has published over 20 articles in scholarly journals. He is the former editor of the Journal of Learning Development in Higher Education. [Image Descriptor: Photo of Chris]