Regression in excel

[life24]

Hello,
I want calculate a , b and c
It's exponential regression?
Thanks

[MrShorty]

There are two basic approaches to regression in Excel:

Standard linear least squares regression, implemented using the LINEST() function. In your case, "linearize" the function by taking the ln() of both sides of the equation. Then apply the LINEST() function to the transformed data. Help file for the LINEST() function: https://support.office.com/en-us/art...a-fa7abf772b6d

Any regression algorithm, including linear least squares, implemented using the built in Solver utility. Guess at the values for the regression parameters, compute the estimated T at each point, your goodness of fit measure, and your objective function (if it is different from your goodness of fit). Call Solver and tell it to minimize/maximize the objective function by changing the regression parameters.

In either case, because your regression equation simplifies to T(n)=a*n^(b+c), I don't think any regression is going to find unique values for b and c. These algorithms will find a value for b+c, but, without more information about b and c, I don't expect a unique solution for b and c to be found.

That is a quick overview, where do you get stuck?

[A.Clubb]

Hi

Would the Data Analysis addin work for you? I calculated Log(Y) for each Y using =LN()

I can't attach spreadsheet for some reason, but SOME of the outputs for your data:

SUMMARY OUTPUT

Regression Statistics
Multiple R 0.990667078
R Square 0.981421259
Adjusted R Square 0.977705511
Standard Error 0.511598611
Observations 7

ANOVA
df SS MS F Significance F
Regression 1 69.13021352 69.13021352 264.1248022 1.60814E-05
Residual 5 1.308665694 0.261733139
Total 6 70.43887921

Coefficients Standard Error t Stat P-value Lower 95% Upper 95% Lower 95.0% Upper 95.0%
Intercept 0.689759105 0.432379743 1.595262305 0.171538947 -0.421708408 1.801226618 -0.421708408 1.801226618
X Variable 1 1.571284887 0.09668305 16.25191688 1.60814E-05 1.322753196 1.819816579 1.322753196 1.819816579

Regards
Alan

[PietBom]

I used the Solver and came to this

[PietBom]

and made it a bit nicer.............

[PietBom]

@Life24,
Was it usefull ?