Polynomial Regression -- explained

This article requires the knowledge of Linear Regression. If you haven't heard of it, then please check out an article on Linear Regression before you proceed here. Till now we assumed that the relationship between independent variable X and dependent Y can be represented with a straight line. But what if when we can't represent the relationship in a straight line because the data might not be linearly separable? In such kind of scenario we can look for polynomial regression.