What is correlation?
Often, the term correlation is used to explain the connection between the phenomena of mathematics and statistical specialists. Further we will tell about what correlation is.
The word "correlation" itself is of Latin origin (from correlatio) and literally means "relationship, interrelation". Therefore, sometimes you can find not just a correlation, but a correlation dependence, which is very similar in meaning.
Correlation (or correlation) is a relationship of two or more random units, identified statistically. Thus, the phenomenon of correlation demonstrates the change of one quantity under the action of another. For example, with the increase in the number of books read, the number of students' learned knowledge increases. In this example, one can, of course, argue about the presence of such a direct correlation, because other parameters interfere. But in general, this may be the case, and the correlation will tell about the relationship between the number of books read and the learned knowledge.
It is worth noting that the correlation may be in one sample of subjects, but not manifest itself in another.