Relationship between variables

The relationship between variables is as follows:

1. correlation.

When the independent variable has a certain value and the dependent variable has a certain randomness, the relationship between the two variables is called correlation, that is, correlation is an uncertain relationship.

When the value of one variable changes from small to large and the value of another variable changes from small to large, the two variables are positively correlated.

When the value of one variable changes from small to large and the value of another variable changes from large to small, the two variables are negatively correlated.

Pay attention to the similarities and differences of correlation and function;

* * * Similarity: Both refer to the relationship between two variables.

Difference: the functional relationship is deterministic, which reflects the causal relationship; Correlation is an uncertain relationship, not necessarily a causal relationship, but a concomitant relationship.

2. scatter diagram. From the scatter chart, the points are scattered from the lower left corner to the upper right corner, and the correlation between the two variables is called positive correlation, while the points are scattered from the upper left corner to the lower right corner, and the correlation between the two variables is negative correlation.

What is relevance:

Correlation refers to the relationship between the changes of multiple variables, which changes within a certain range according to certain laws. Correlation, even a strong correlation, does not mean causality, and can only be inferred according to relevant circumstances.

Relevance is the most extensive in life, covering almost all aspects of life, and many people will regard it as a causal relationship.

The following two very good jokes can help to understand the difference between relevance and causality:

The big tree in front of the house is old and the national economy is increasing year by year, so this big tree affects the national economy.

(2) Every year, a large number of people who have been to the hospital get sick, so the hospital is related to illness. Does that mean that people won't get sick if they don't go to the hospital?

As we all know, no matter whether the economy is flat or declining, big trees will grow up or die, and there is no causal relationship; It is because people are sick that they have to go to the hospital, so there are so many patients in the hospital, but this does not mean that "going to the hospital" is the reason for "being sick".