doubt regarding covariance

[Tanuja Nair]

Good evening,

I am still finding difficulty in calculating the sample and population covariance. Can you please explain this to me?

Thank you

[Malabika Guha Mustafi]

@ Tanuja , it is quite straight.
 First step. take mean of x variables.

compute  (xi-x mean) for each element.

Same things for y variable also.

Take mean of y variable  and compute (yi-ymean) for each element.

Now, multiply the two values for each corresponding data point.

That mean if you take first data point for x ( xi-x mean) where x=1

then it should be multiplied by (yi-y mean) where I=1 for y value.

Then take the sum of this each data points product ( xi-x mean) *( yi-y mean).

Finally, for population covariance just divide the sum by N( n is the total observations).

For , sample covariance just divide the sum by (n-1)[n is the total observations).

[Tanuja Nair]

thank you so much! 

[Malabika Guha Mustafi]

Please correct it,

That means if you take first data point for x ( xi-x mean) where i=1

then it should be multiplied by (yi-y mean) where i=1 for y value.