The term variable is used when it is meant that some things, situations and even that people have a recurrence towards instability and inconstancy. This roughly and very informally of course, but if we get a little more serious and formal, we say that variable is what we said and it is also a symbol that represents an unspecified or identified element of a given set. This same set is called the universal set of the variable and each member of that set is a value of the variable.
For example y, in order to make it clearer, "X" is a variable of the following universe 2, 4, 6, 8, so x will have any of those values and can be replaced by any even value less than 9.
In this case and as we saw through the example, the variable is an element of a formula that can be substituted or acquire any value within that universe; outside of it, obviously, this will be impossible. Meanwhile, there are different types of variables, we find the dependent and independent on the one hand and on the other with the qualitative and quantitative. The first are those that will depend on the value assumed by the other variables and the second are those that can undergo changes. per se in its value and affect that of the others. For example, in a model in which the price of an object is one peso, the number of objects that I consider constitutes an independent variable, while the final price, when directly linked to the number of objects, will be the dependent variable . In this simple variant, the independent variable "four objects" will correspond to the dependent variable "four weights".
On the other hand, qualitative variables express different qualities, characteristics or modalities and the quantitative they are stated only in numbers. Thus, parameters as different from each other as a price, blood pressure, the number of legs of an animal or the number of parts of an engine are quantitative variables. Instead, hair color, car brands from a dealership, authors present in a library, or components of the stock of a room are qualitative variables. In this sense, it is interesting that we notice a special type of qualitative variable, which is called a dichotomous variable: "yes" or "no", only 2 possible options. When you want to analyze some more or less complex variables with statistical techniques, a widely used strategy is to replace a dichotomous variable with a numerical code; the "yes" becomes "1" and the "no" becomes "0". This trick has been expanded so that, when we come across qualitative variables with more than 2 possible options, it is possible to convert them to numerical data and thus be able to extract information. The best example is the replacement of the months of the year by their order in the calendar: "January" (qualitative variable) is "1" (numerical variable) ... and so on until "December" which becomes "12".
By analyzing variables Numerous advances have been made in areas of human knowledge as disparate as mathematics, economics, health sciences, archeology, and geology. Therefore, knowing these everyday "fellow travelers" makes it easier to better understand the world around us.
