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I use datas in excel to produce a graphic.

Then I make a regression, and have an equation. I'd like to know what value would be obtained from the regression (for example, x = 7,6 is the value for which I wanna know an estimation of y).

It is an approximation with a 6 degree polynome.

One wimple method would be this : I have the equation, so I could use it

However, I wondered if there is a fast method to do it? Like I enter 7,6 somewhere to have the result quickly?

Cher
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1 Answers1

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if you are looking at a linear regression line (straight line) you could try the forecast formula

=forecast(X, Known Ys, Known Xs)

you could also build your own equation automatically from 

=linest(...)

I found the following on a site describing the capabilities of the linest function in excel:

In addition to using LOGEST to calculate statistics for other regression types, you can use LINEST to calculate a range of other regression types by entering functions of the x and y variables as the x and y series for LINEST. For example, the following formula:

=LINEST(yvalues, xvalues^COLUMN($A:$C))

works when you have a single column of y-values and a single column of x-values to calculate the cubic (polynomial of order 3) approximation of the form:

y = m1*x + m2*x^2 + m3*x^3 + b

You can adjust this formula to calculate other types of regression, but in some cases it requires the adjustment of the output values and other statistics.

or look at:

=trend
Forward Ed
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  • ahh well that changes everything! I cant remember the math behind coming up with regression so I can't set up a formula for a polynomial for you. sorry. – Forward Ed Mar 26 '16 at 23:28
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    take a look at this stackoverflow article on cubic and quadratic regression, you may be able to extrapolate it to the 6th degree polynomial: [http://stackoverflow.com/questions/10857252/quadratic-and-cubic-regression-in-excel](http://stackoverflow.com/questions/10857252/quadratic-and-cubic-regression-in-excel) – Forward Ed Mar 27 '16 at 00:42