# Correlation

**Correlation** is a **relationship** or dependency that exists **between two variables**.

If a correlation exists, it is said that the variables are correlated or there is a correlation between them.

### Types of Correlation

**Positive Correlation**

A positive correlation occurs when an increase in one variable increases the other variable.

The line corresponding to the scatter plot is an increasing line.

**Negative Correlation**

A negative correlation occurs when an increase in one variable decreases the other.

The line corresponding to the scatter plot is a decreasing line.

**No Correlation**

No correlation occurs when there is no linear dependency between the variables.

**Perfect Correlation**

A perfect correlation occurs when there is a funcional dependency between the variables.

In this case all the points are in a straight line.

**Strong Correlation**

A correlation is stronger the closer the points are located to one another on the line.

**Weak Correlation**

A correlation is weaker the farther apart the points are located to one another on the line.