Throughout this article we will see some examples of qualitative variables highly studied in science, to facilitate understanding of the concept.
What are the qualitative variables?
Research helps professionals from different disciplines to improve their understanding of the dimensions of reality they are dealing with. Through research, it is possible to assess whether a drug or treatment is effective or not, or if it is more effective than another, and even allows the creation of technologies and scientific advances of great importance. relevance.
But to investigate it is necessary to keep in mind that there are many things that affect what we want to analyze. There are countless variables to consider. And the study of these and their interaction is fundamental for the scientific explanation of reality.
Within the different variables we can find two big groups depending on how we can come to treat them. Some of them make it possible to measure aspects of reality and to observe mathematical relationships between their values: quantitative variables. Others allow us to see that there is a quality or not that we observe, but do not allow its measurement (especially when talking about abstract elements): these are the qualitative variables.
Characteristics of this scientific concept
It is understood as a qualitative variable to any type of characteristic or category that it is used to classify a reality plot into various non-numeric values which make it possible to value the presence of differences or fluctuations in relation to this characteristic between the different subjects to be analyzed.
The qualitative variable is one that focuses on the quality, condition or characteristic and ranks reality according to numerically non-quantifiable categories (as opposed to quantitative categories which allow the quantities of these variables to be evaluated).
In other words, qualitative variables are those whose values are not measurable with measuring instruments and which they do not present by themselves a measurable quantity. Thus, where we find examples of qualitative variables, we will mainly find indications as to whether or not the studied subjects have a quality that cannot be accumulated less and more quantity by using values with the same numerical distance from each other.
These variables can be both nominal (only serve to differentiate subjects into different categories) and ordinal (which in addition to the above allow you to establish an order, although this does not allow to observe relationships mathematics between their 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 is a series of examples of typical qualitative variables, but it should be remembered that it is often possible to make such a variable exploitable and quantitative.
Probably the most common qualitative variable in scientific research, at least when we analyze aspects related to human behavior and health. This variable has two values in its most traditional conception, or three if one takes into account the existence of intersex people. It should be noted that we are talking about sex on a biological level, not gender or gender identity.
Thus, we could find the values male, female and intersex, which establish a categorization of subjects in such a way that the category in itself establishes that the subject is part of one or the other group, being a qualitative nominal. : being something or another does not allow to establish a hierarchy or an order nor to carry out mathematical operations or transformations with its values.
2. Gender / gender 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 only this category a characteristic of his person that is not directly quantifiable.
3. Sexual orientation
Another nominal qualitative variable may be sexual orientation: the category in question establishes a distinctive element without order or numerical relation. Heterosexual, homosexual, bisexual, asexual, pansexual … there are many possible categories.
4. Marital status
Like sex, marital status is another categorical categorical variable, values establish a quality or property in which different people can be differentiated but without any numerical relationship between their values. It is only established whether or not the subject has a partner. Single, common-law or widower are among the most common and well-known values, as well as people who are separated or divorced.
5. Ethnicity / race
Another example of the qualitative variable that appears most in the social sciences is that of ethnicity or race, in this case also being a nominal type 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 any order or numerical relationship between these factors.
6. Religious denomination
The religious denomination of a person can be regarded as a type of qualitative variable: it establishes only one quality of person.
To be an atheist, agnostic, Christian, Muslim, Jewish, Hindu, Buddhist or a member of another of the many existing religious denominations is something that can differentiate people’s beliefs and ways of being, but without any sort of ordination or numerical relationship between them.
Our profession or trade is also a nominal qualitative variable. Just be a psychologist, doctor, architect, mason, plumber or priest it allows us to categorize ourselves within a collectiveBut it does not order people or establish numerical relationships between different professions.
This time, we are dealing with 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 do not have numeric values per se.
So we can see people without education, with primary, secondary and higher education. One is no more valuable than another, but someone with a high school education must have had some primary education before, for example.
9. Socioeconomic level
Like education, it is an ordinal-type qualitative variable: having a high socio-economic level implies a larger share of this variable than a low-level person, although a numerical relationship cannot be established. .
While we mentioned that occupation is a nominal qualitative variable, the place we occupy within this profession can be considered ordinal (Although always qualitative): A hierarchical order can be established between the different positions, for example from soldier to general or from assistant kitchen to chef.
Green, blue, red, white … iColor is another example of a categorical dummy variable, Given only indicates to us a quality of the object that differentiates it from others. We cannot establish any kind of numerical relationship between its values. However, it should be borne in mind that this variable could become quantitative if, instead of color, we measure the wavelength (in which there are numerical values that can be used.
12. Blood group
Another categorical categorical variable may be the blood group. Have group A, B, AB or O at their positive or negative levels it does not allow us to place an order or establish digital relationships (one who has A + blood does not have twice as much as B +, for example).
The brand of the products we use is another possible qualitative variable of a nominal type, which it can be used for example in market research.
And is that the mark itself can only provide information that is presented or not this value of the variable. However, it should be borne in mind that if we analyze the number or frequency of use of this brand, we will already be using a quantitative variable.
By itself, mood (from which we could derive in itself different variables such as joy, sadness, etc.) is a qualitative variable.
Another thing is that by means of specialized instruments, a representative measurement of the state of mind can be made during the functioning of this phenomenon (for example, we can use tests like BDI to measure the levels of depression ); but by itself being sad, happy or euthymic offers values of a variable which do not allow to establish numerical relations between them.
15. Name (and first names)
We probably don’t think of them as a variable, but the truth is that our first and last names can be viewed and treated as categorical dummy variables.
Jaume is not Pablo, but you cannot establish an order or visualize a numerical relation with these values (since if for example we proposed to count the number of Jaimes and Pablos, the variable would already become Number of Jaimes / Pablos and it would already be quantitative).
The same goes for surnames. They are used to bring together members of the same family, but they are not used to order them nor is it possible to establish numerical relationships with this variable per se.
- Babbie, ER (2009). The practice of social research. Belmont: Wadsworth Publishing.
- Bunge, M. (1969). Science: its method and its philosophy. Pamplona: Laetoli.