A variable , in the field of math , is a symbol that can appear in a function, an algorithm, a proposition or a formula, adopting different values . By establishing links with other variables, they can contribute to the development of a theory or a hypothesis, acquiring the denomination of constructs .
It is possible to differentiate between different kinds of variables depending on the context. The qualitative variables are those that allow the expression of a characteristic , a category , a attribute or one quality .
It is interesting in this sense to know the etymological origin of the two words that make up the term at hand. Thus, we can establish the following information:
-Variable comes from Latin, specifically "variabilis" that is the result of the sum of two components: the verb "variare", which can be translated as "change of aspect", and the suffix "-able", which is used to indicate possibility.
-Qualitative, on the other hand, also derives from Latin. In his case of the word "qualitativus", which is composed of two parts: the noun "qualitas", which means "quality", and the suffix "-tivo". This is used to indicate a passive or active relationship.
We said that the variables can adopt different values . In the case of qualitative variables, if they can only adopt two values they receive the qualification of dichotomous . For example: a person can be "live" or "dead", there is no third option. This qualitative variable, therefore, is dichotomous.
If the qualitative variable can acquire a number of values greater than two, it is called politomics . In this group In turn, a distinction can be made between qualitative nominal polytomic variables and qualitative ordinal polytomic variables.
The qualitative nominal politomic variables they adopt values that cannot be ordered . A pant can be "blue", "black", "green", "Red", "yellow" or "pink", to cite some possibilities, without there being a criterion or a hierarchy that allows the ordering of the attribute (the colour ).
In the same way, another example that can help us understand what the qualitative nominal variables are is the one that refers to the marital status of a person. Thus, it can be single, married, widowed, divorced or separated without establishing any kind of rank or hierarchy with respect to those possibilities.
The ordinal politomic qualitative variables Instead, they acquire values that can be sorted according to a scale . A sound can be "weak", "moderate" or "intense", three values that are ordered from least to greatest (or vice versa) according to their characteristics.
More examples of ordinal or quasi-quantitative qualitative variables are the following:
-Within an athletics competition, three medals are awarded that follow a hierarchy as to who came first, second and third to the goal. We are referring to gold, silver and bronze.
-With regard to the grade of an exam, these variables are also established with the corresponding order or hierarchy. Thus, a student may have obtained an outstanding grade, a notable, a good, an approval or a suspense.