Future value calculation

[Villalobos]

Hello,

I try to calculate the future value by polynomial regression but I have doubt there are some mistake in my formulae. Please, could somebody check it?

 

[Hui]

It is unlikely that there will be two factors of ^2
=B7+$G$4+(B7^2)*$F$4+(B7^3)*$E$4+(B7^2)+$H$4

Typically a formula would be in the format of
=Factor1*(B7^4)+Factor2*(B7^3)+Factor3*(B7^2)+Factor4*(B7)+Factor5

But as I don't know your source it may be ok ?

Also going backwards there is a very poor correlation with your data
A B Past values
1 15 1.9
2 13 5.9
3 16 12.0

 

[Villalobos]

Hi Hui,

Thank you the response.
I would have one more question... how must to determine correctly the number of coefficient and the level of polynomial?

 

[Hui]

As an introduction, have a read of:
http://chandoo.org/wp/2011/01/24/trendlines-and-forecasting-in-excel/
http://chandoo.org/wp/2011/01/26/trendlines-and-forecasting-in-excel-part-2/
+
http://chandoo.org/wp/2011/01/27/trendlines-and-forecasting-in-excel-part-3/

 

[Villalobos]

thanks the links