# Let’s have fun with Correlation :-O

Whenever you will read any post or paper related to Machine-Learning or Data-Science you will get word ‘Correlation’ many times and how it’s value is important in your model Building.

A simple definition of Correlation: A mutual relationship or connection between two or more things. (that’s layman’s definition and It should be enough most of the times ;) )

Coefficient of Correlation is just an integer, From which we understand how two or more things are related to each-other. As we discussed Coefficient of Correlation is an integer so **it could be +ve or -ve and value of correlation decides how two data-sets effect each other.**

Following two images tell lot about Correlation and it’s Value.

**What is Covariance?**

Now if you still feel that something is really missing we should talk about Variance:

**Let’s Remove Co from Covariance.**

Variance is Measurement of randomness. So How you would calculate Variance of Data?

**Give me data:**

**Data = [4,5,6,7,12,20]**

I will find means and subtract it from each individual- Isn’t that Mean-Deviation ? :D OMG!

Have a look at the following Picture: