how to use multiple regression

[Dave in naigeria]

Please can anyone help me solve this problem.

Use linest function to estimate what A,B,C & D will be, Compare them.

Y= a+bx+cx^2+dx^3

assum x=0, x=1, .................. x= 100

Calculate the corresponding value of Y. Choose any coefficient for the
constant.

Thanks and regards,
Dave

[Conrad Carlberg]

As written, your post is a little puzzling.

To use LINEST() you're going to need to start with both a series of X values
and a series of Y values. So you won't "Calculate the corresponding value of
Y," but you can use the regression coefficients and the constant to get
estimates of Y. If what you're really after is the Y estimates, the TREND()
function is more straightforward than LINEST() because it calculates the
equation and applies it to your X values to return the Y estimates. But if
you use LINEST(), and assuming you have Y in column A, X in column B, X^2 in
column C and X^3 in column D, start by selecting a blank range four columns
wide and five rows high, type this formula:

=LINEST(A1:A100,B1:D100,,TRUE)

and array-enter it with CTRL-SHIFT-ENTER instead of just ENTER. You can also
square and cube X in the arguments:

=LINEST(A1:A100,B1:B100^{1,2,3},,TRUE)

What do you want to compare A,B,C & D to? Zero? Something else? Use the
standard errors.

You can force the constant to zero using LINEST's third argument but in
general it's a bad idea.

--
C^2
Conrad Carlberg

Excel Sales Forecasting for Dummies, Wiley, 2005


"Dave in naigeria" <Dave in [email protected]> wrote in
message news:[email protected]...
> Please can anyone help me solve this problem.
>
> Use linest function to estimate what A,B,C & D will be, Compare them.
>
> Y= a+bx+cx^2+dx^3
>
> assum x=0, x=1, .................. x= 100
>
> Calculate the corresponding value of Y. Choose any coefficient for the
> constant.
>
> Thanks and regards,
> Dave

[Dave in naigeria]

Thanks Conrad.
The equation is actually not written well x^2 means x squared and x^3 means
x cube.so the equation is

Y= a + bx + cxsquared + dxcube

"Conrad Carlberg" wrote:

> As written, your post is a little puzzling.
>
> To use LINEST() you're going to need to start with both a series of X values
> and a series of Y values. So you won't "Calculate the corresponding value of
> Y," but you can use the regression coefficients and the constant to get
> estimates of Y. If what you're really after is the Y estimates, the TREND()
> function is more straightforward than LINEST() because it calculates the
> equation and applies it to your X values to return the Y estimates. But if
> you use LINEST(), and assuming you have Y in column A, X in column B, X^2 in
> column C and X^3 in column D, start by selecting a blank range four columns
> wide and five rows high, type this formula:
>
> =LINEST(A1:A100,B1:D100,,TRUE)
>
> and array-enter it with CTRL-SHIFT-ENTER instead of just ENTER. You can also
> square and cube X in the arguments:
>
> =LINEST(A1:A100,B1:B100^{1,2,3},,TRUE)
>
> What do you want to compare A,B,C & D to? Zero? Something else? Use the
> standard errors.
>
> You can force the constant to zero using LINEST's third argument but in
> general it's a bad idea.
>
> --
> C^2
> Conrad Carlberg
>
> Excel Sales Forecasting for Dummies, Wiley, 2005
>
>
> "Dave in naigeria" <Dave in [email protected]> wrote in
> message news:[email protected]...
> > Please can anyone help me solve this problem.
> >
> > Use linest function to estimate what A,B,C & D will be, Compare them.
> >
> > Y= a+bx+cx^2+dx^3
> >
> > assum x=0, x=1, .................. x= 100
> >
> > Calculate the corresponding value of Y. Choose any coefficient for the
> > constant.
> >
> > Thanks and regards,
> > Dave
>
>
>

[Conrad Carlberg]

>The equation is actually not written well x^2 means x squared and x^3 means
> x cube.so the equation is
>
> Y= a + bx + cxsquared + dxcube

That much was clear.
--
C^2
Conrad Carlberg

Excel Sales Forecasting for Dummies, Wiley, 2005


"Dave in naigeria" <[email protected]> wrote in
message news:[email protected]...
> Thanks Conrad.
> The equation is actually not written well x^2 means x squared and x^3
means
> x cube.so the equation is
>
> Y= a + bx + cxsquared + dxcube
>
> "Conrad Carlberg" wrote:
>
> > As written, your post is a little puzzling.
> >
> > To use LINEST() you're going to need to start with both a series of X
values
> > and a series of Y values. So you won't "Calculate the corresponding
value of
> > Y," but you can use the regression coefficients and the constant to get
> > estimates of Y. If what you're really after is the Y estimates, the
TREND()
> > function is more straightforward than LINEST() because it calculates the
> > equation and applies it to your X values to return the Y estimates. But
if
> > you use LINEST(), and assuming you have Y in column A, X in column B,
X^2 in
> > column C and X^3 in column D, start by selecting a blank range four
columns
> > wide and five rows high, type this formula:
> >
> > =LINEST(A1:A100,B1:D100,,TRUE)
> >
> > and array-enter it with CTRL-SHIFT-ENTER instead of just ENTER. You can
also
> > square and cube X in the arguments:
> >
> > =LINEST(A1:A100,B1:B100^{1,2,3},,TRUE)
> >
> > What do you want to compare A,B,C & D to? Zero? Something else? Use the
> > standard errors.
> >
> > You can force the constant to zero using LINEST's third argument but in
> > general it's a bad idea.
> >
> > --
> > C^2
> > Conrad Carlberg
> >
> > Excel Sales Forecasting for Dummies, Wiley, 2005
> >
> >
> > "Dave in naigeria" <Dave in [email protected]> wrote in
> > message news:[email protected]...
> > > Please can anyone help me solve this problem.
> > >
> > > Use linest function to estimate what A,B,C & D will be, Compare them.
> > >
> > > Y= a+bx+cx^2+dx^3
> > >
> > > assum x=0, x=1, .................. x= 100
> > >
> > > Calculate the corresponding value of Y. Choose any coefficient for the
> > > constant.
> > >
> > > Thanks and regards,
> > > Dave
> >
> >
> >

[Jerry W. Lewis]

Conrad already explained how to fit a cubic polynomial with LINEST. An
alternative to using the LINEST coefficients to predict y values at 1 to
100 would be

=TREND(known_ys,known_xs^{1,2,3},ROW(A1:A100))

array entered.

Jerry

Dave in naigeria wrote:

> Please can anyone help me solve this problem.
>
> Use linest function to estimate what A,B,C & D will be, Compare them.
>
> Y= a+bx+cx^2+dx^3
>
> assum x=0, x=1, .................. x= 100
>
> Calculate the corresponding value of Y. Choose any coefficient for the
> constant.
>
> Thanks and regards,
> Dave