Re: R Square?

I have equations like:
x y ypred
1 11 12.879
2 5.5 123.5346
3 1 253.64
4 23 379.48
5 4 495.078
6 5 612.2066
where I get ypred from excel and add trendline I've got:
ypred = 0.7396x4 - 11.35x3 + 59.337x2 - 120.43x + 83.583
Rsquare = 0.3797

I want to know how Excel find it.
First I square the pearson correlation (this is define as function
rsq(x,y) in excel)
Instead of using rsq(x,y) I use rsq(y, ypred), I've got:
Rsquare = 0.00507954 (not the same as above)

Second I try to calculate Rsquare using
Rsq = 1 - SS(regression)/SS(total)
I've got:
Rsquare = -2594.624977 (not the same as above)

I wonder how excel trendline find the Rsquare ?

Best Regards,
pujo

.

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