Difference Between Qualitative and Quantitative Variable
The difference between a qualitative and a quantitative variable lies mainly in what each one expresses. This, despite the fact that in both cases numerical values can be assigned.
To better understand the difference between these two types of statistical variables , we will develop throughout this article the main points of disagreement.
What does a qualitative variable express? and a quantitative?
On the one hand, the qualitative variable expresses an observable characteristic or quality of the subject studied. This can be explained through words, for example, a person's eye color can be black, brown, blue or green.
In contrast, a quantitative variable cannot be associated with a quality, but rather is a quantifiable factor or property that takes numerical values, such as a person's age.
Are the quantitative and qualitative variables measurable?
Qualitative variables are not measurable. For example, a person's nationality is not measurable. A citizen is not 85% Spanish, because he is simply Spanish.
Now, this is not to say that qualitative variables cannot be associated with a number for statistical purposes. For example, to process a survey, you can assign the number 1 to people who said they are single, 2 to those who are married, and 3 to those who are divorced.
On the other hand, quantitative variables are measurable, for example, an individual's body temperature, which can be 37, 36, 35, or 39 degrees Celsius if they have a high fever.
Specific and relative variables
Another point to keep in mind is that qualitative variables are usually more relative than quantitative ones. Or, to understand it another way, we can say that quantitative variables are more exact.
For example, a qualitative variable could be the level of satisfaction of a client, after receiving a telephone assistance service. The consumer will have to mark from 1 to 5, with 1 being the minimum and 5 the maximum satisfaction.
In this case, the respondent is being forced to dial a number, but that does not mean that everyone who dialed 4 felt the same degree of satisfaction.
In contrast, a quantitative variable is more exact, for example, the amount of rice in a sack that can be weighed on a scale. In this way, we will obtain an amount of kilograms, grams, or even tons.
As we can see, in the case of the qualitative variable, the assignment of numerical values is "forced" for the subsequent statistical study. However, this does not mean that they are measurable and exact variables.