How to Check Whether Data is Linear or not? 😕

*Linear function: *
Can be simply defined as a function which always follows the principle of :

input/output = constant.

A linear equation is always a polynomial of degree 1 (for example x+2y+3=0). In the two dimensional cases, they always form lines; in other dimensions, they might also form planes, points, or hyperplanes. Their “shape” is always perfectly straight, with no curves of any kind. This is why we call them linear equations.

Non-linear function:
Any function that is not linear is simply put, Non-linear. Higher degree polynomials are nonlinear. Trigonometric functions (like sin or cos) are nonlinear. Square roots are nonlinear.

In case you are dealing with predicting numerical value, the technique is to use scatter plots and also apply simple linear regression to the dataset, and then check the least square error. If the least square error shows high accuracy, it can be implied that the dataset is linear in nature, else the dataset is non-linear.