What is Variable:
Variable is an adjective that means that something or someone varies or can vary. It also means "unstable", "changeable" and "fickle".
In mathematics, a variable is a magnitude that can have any value between those included in a set.
It comes from Latin variabĭlis.
Dependent and independent variable
Depending on the relationship of influence of one variable on another, a distinction is made between a dependent and an independent variable.
A dependent variable is a variable whose value is determined by the value of other variables. It is the factor observed and measured in a study. In a function it is usually represented on the coordinate axis and with the symbol "y".
An independent variable is a variable whose value is not determined by another variable. These are variables that may or may not have an influence or be associated with the dependent variable. In a function it is usually represented on the abscissa axis and with the symbol "x".
Quantitative and qualitative variable
A quantitative variable is a variable that can be expressed by a numeric value, which allows you to perform arithmetic operations on it. Examples of quantitative variables are a person's weight, age, and number of children.
Quantitative variables may or may not be grouped. They can also be discrete or continuous.
A qualitative variable is a variable that does not correspond to a numerical value. Examples of qualitative variables are gender, place of birth, and profession.
A discrete variable is a type of quantitative variable that cannot have intermediate values within a set. For example, the number of televisions in a home (0, 1, 2, 3 ...).
Unlike a continuous variable, in the discrete variable there are defined values, while in the continuous variable it can take any value between two numbers.
A random variable is a function that associates each element of a sample space with a real number. This concept is used in statistical studies.
Four types of random variables can be distinguished: discrete, continuous, binomial, and normal.
It is usually represented with symbols in uppercase (for example: "X" and "Y") and in lowercase to indicate specific values.