### What is linear regression? When do we use it?

• Linear regression is a model that assumes a linear relationship between the input variables (X) and the single output variable (y).

With a simple equation:

*y = B0 + B1*x1 + ... + Bn * xN*

• B is regression coefficients, x values are the independent (explanatory) variables and y is dependent variable.

• The case of one explanatory variable is called simple linear regression. For more than one explanatory variable, the process is called multiple linear regression.

**Simple linear regression:**

*y = B0 + B1*x1*

**Multiple linear regression**:

* y = B0 + B1*x1 + ... +
Bn * xN*