How do I form an equation for a Demand Curve by taking data from a Multiple Regression analysis in Excel?

Question

See my previous question and the answer given.

How do I estimate demand using MULTIPE REGRESSION in Microsoft Excel? (there was a long explanation that wouldn't fit in here.)


ANSWER:
Bring up the Data Analysis tool and pick regression from the menu.
Click the fields that says Input Y Range. Then click the top cell of the Dependent Variable. Highlight the entire column. The field should say something like:
$B$2:$B$48
Hit the Tab key -- this should bring you to the field marked Input X Range. Now click on the first cell of the first column of your independent variables. Highlight the entire three columns. You should now have something like the following in the field:
$C$2:$E$48
If the labels are highlighted too, click on the Labels check box, If not, leave it alone. Hit OK.
Your regression results should show up in a new sheet.

SUMMARY OUTPUT
Regression Statistics
Multiple R0.835478305
R Square0.698023997
Ran out of room. Email me for regression results: [e-mail]

Answer 1

there should be a column of coefficients. estimated demand is equal to sum of products of those coefficients and corresponding variables, plus the constant.

I.e. demand = constant +var1*coef1+var2*coef2+...

Answer 2

I would be VERY cautious about running a regression in excel. Especially if your data is poorly conditioned. Numerical error is not as closely watched in Excel. You should probably do your regression analysis in R, SAS, Matlab, or SPSS.