15 examples of qualitative variables, with explanations

Throughout this article we will see some examples of qualitative variables heavily studied in science, in order to make the concept easier to understand.

• Related article: "The 15 types of research (and characteristics)"

What are qualitative variables?

Research helps professionals from different disciplines to improve their understanding of the dimensions of reality with which they deal. Thanks to research, it is possible to assess whether or not a drug or treatment is effective, or that is more effective than another, and even allows to create technologies and scientific advances of great relevance.

But to investigate it is necessary to bear in mind that there are many elements that affect what we want to analyze. There are countless variables to take into account. And the study of these and their interaction is fundamental for the scientific explanation of reality.

Within the different variables, we can find two large groups depending on the way in which we can treat them. Some of them allow us to measure aspects of reality and observe mathematical relationships between their values: quantitative variables. Others allow us to see that there is a quality or not that we are observing, but do not allow its measurement (especially when we talk about abstract elements):

it is about the qualitative variables.

Characteristics of this scientific concept

A qualitative variable is understood to be any type of characteristic or category that serves to classify a plot of reality in several non-numerical values that allow assessing the presence of differences or fluctuations with respect to said characteristic between the different subjects to be analyzed.

The qualitative variable is one that focuses on the quality, condition or characteristic and classifies reality based on Non-quantifiable categories numerically (unlike quantitative ones that allow valuing quantities of said variables).

In other words, qualitative variables are those whose values ​​are not measurable with measuring instruments and that they do not present a measurable amount by themselves. Thus, wherever we find examples of qualitative variables, we will mainly find indications about whether the subjects studied have or do not have a quality that cannot be accumulated from less to more quantity using values ​​with the same numerical distance each.

These variables can be both nominal (they only serve to differentiate subjects into different categories) and ordinal (which in addition to the above allow to establish an order, although it does not allow to observe mathematical relationships between values). They can also be dichotomous (when there are only two possible values) or polynomial (when the variable can have more than two possible values).

15 examples of qualitative variables

Below you will find a series of examples of typical qualitative variables, although you must take into account that it is often possible to make a variable of this type operable and quantitative kind.

1. Sex

Probably the most common qualitative variable in scientific research, at least when we analyze aspects related to behavior and human health. This variable has two values ​​in its most traditional conception, or three if we take into account the existence of intersex people. It is necessary to take into account that we talk about sex on a biological level, not about sexual or gender identity.

Thus, we could find the values ​​man, woman and intersex, which establish a categorization of the subjects in such a way that the category itself only establishes that the subject It is part of one or the other group, being a nominal qualitative: being one thing or another does not allow establishing a hierarchy or order or performing mathematical operations or transformations with its values.

2. Gender / sexual identity

In addition to biological sex, sexual or gender identity is also a nominal qualitative variable. People can be cisgender or transgender, for example, expressing this category only a characteristic of your person which is not directly quantifiable.

3. Sexual orientation

Another nominal qualitative variable can be sexual orientation: the category in question establishes a distinctive element without there being any type of order or numerical relationship. Heterosexual, homosexual, bisexual, asexual, pansexual... there are a lot of possible categories.

4. Civil status

Like sex, marital status is another qualitative variable of a nominal type, whose values ​​establish a quality or property in which different people can be differentiated but without there being any numerical relationship between their values. It only establishes whether or not the subject has a partner. Single, married / common-law partner or widower are some of the most common and well-known values, as well as separated or divorced.

5. Ethnicity / Race

Another example of a qualitative variable that appears more in social sciences is that of ethnicity or race, in this case, it is also a nominal variable. And it is that being, for example, Caucasian or African American (among others) allows us to distinguish different ethnic groups, but without there being an order or numerical relationship between these factors.

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6. Religious confession

The religious confession of a person can be considered a type of qualitative variable: it only establishes a quality of a person.

Be an atheist, agnostic, Christian, Muslim, Jewish, Hindu, Buddhist or member of another of the many existing religious confessions is something that can differentiate the beliefs and the way of being of people, but without there being any sort of order or numerical relationship between they.

7. Profession

Our profession or trade is also a nominal qualitative variable. Be a psychologist, doctor, architect, bricklayer, plumber or priest simply allows us to categorize ourselves within a collective, but it does not allow ordering people or establishing numerical relationships between different professions.

8. Scholarship

This time we are facing a type of qualitative variable of ordinal type: there is a progression between the different levels and allows comparisons to be made using ordered categories, even if they don't have numeric values ​​per se.

Thus, we can see people without studies, with primary studies, secondary studies and higher studies. One is not more valuable than the other, but someone with secondary education must have done primary studies before, for example.

9. Socioeconomic level

Like schooling, it is a qualitative variable of an ordinal type: having a high socioeconomic level implies a higher degree of this variable than someone with a low level, although a numerical relationship cannot be established.

10. Position

Although we have mentioned that profession is a nominal qualitative variable, the position we occupy within said profession can be considered ordinal (although it is still qualitative): a hierarchical order can be established between the different positions, for example from private to general or from kitchen servant to chef.

11. Colour

Green, blue, red, white... EColor is another example of a nominal qualitative variableGiven only indicates a quality of the object that differentiates it from others. We cannot establish any kind of numerical relationship between their values. Now, it must be taken into account that this variable could become quantitative if instead of color we measure wavelength (in which there are operable numerical values.

12. Blood type

Another nominal qualitative variable can be blood group. Have group A, B, AB or O in its positive or negative levels it does not allow us to do an ordering or establish numerical relationships (who has A + blood does not have twice that of B +, for example).

13. Brand

The brand of the products we use is another possible qualitative variable of a nominal type, which can be used for example in market research.

And it is that the brand itself can only offer us information that said value of the variable is presented or not. Now, it must be borne in mind that if we go on to analyze the number or frequency of use of said brand, we will already be using a quantitative variable.

14. Mood

By itself, the state of mind (from which we could extract different variables such as happiness, sadness, etc.) is a qualitative variable.

Another thing is that by means of specialized instruments a representative measurement of the state of the encouragement to operationalize this phenomenon (for example, we can use tests such as the BDI to measure levels of depression); but by itself being sad, happy or euthymic offers values ​​of a variable that does not allow numerical relationships to be established.

15. Name and surname)

We probably do not usually think of them as a variable, but the truth is that our name and surname can be considered and treated as nominal qualitative variables.

Jaime is not Pablo, but you cannot establish an order or visualize any numerical relationship with these values ​​(since if by For example, we propose to count the number of Jaimes and Pablos, the variable would now become Number of Jaimes / Pablos and this would already be quantitative).

The same goes for surnames. They serve us to group the members of the same family, but they do not serve to order them nor can numerical relationships be established with this variable per se.

Bibliographic references:

• Babbie, E.R. (2009). The Practice of Social Research. Belmont: Wadsworth Publishing.
• Bunge, M. (1969). Science, its method and philosophy. Pamplona: Laetoli.