@MandyGeorge I really Appreciate the effort you took to explaining the formula. Thank you so much. It is very much clear now. Once again thanks a lot..     

Thank you. @MandyGeorge . Request to confirm whether the existing 'Linear regression: Predicted Y' function is built with all the other formulas? like Slope and intercept.

Hello @MandyGeorge, Thank you so much for the reply and explanations. I guess I need to go through this again.  However, Can you please help me understand for some days data is showing negative.? is it has any relation between the upper right hand date range selection?  

I have created the below metrics. However, I am not sure whether it is correct? and why predicted data keeps on changing?