# Thread: A problem of several dummies in regression(Excel)

1. ## A problem of several dummies in regression(Excel)

Hello, everyone! In Excel I tried to make a regression equation with several dummies. The task is:

Include the manufacturer in a multiple linear regression analysis using a "dummy" variable. Does it appear that some manufacturers can command a premium price? Hint: You will need to use a set of indicator variables. (Round your answers to 2 decimal places.Negative amounts should be indicated by a minus sign.)

Price =b0+b1Screen+b2Manufacturer Sharp +b3Manufacturer Sony ???

What are the right cofficients?
Can someone show a regression analysis in Excel? I made a column for M.Sharp and M.Sony, but the result is incorrect.

The basic regression equation is: Price =-2484+101 Screen

The sample and sample in Excel are in attachment!

3. ## Re: A problem of several dummies in regression(Excel)

Thank you! but the problem is in the task: how to make an equation with several dummies.

4. ## Re: A problem of several dummies in regression(Excel)

Hi Lisa!

What do you mean with "how to make an equation with several dummies"?

You already have such an equation: "Price =b0+b1Screen+b2Manufacturer Sharp +b3Manufacturer Sony".

You have the right dummy variables.
For your regression analysis you should put Screen, M.Sharp, and M.Sony in adjacent columns.
Then click and go as chiro suggested.

Note that if you also include M.Samsung, you'll get an ill-conditioned problem that does not have a solution.

As it is, you should get:

 Coefficients P-value Intersection -2307.005766 0.000159734 screen 94.09753363 4.81628E-08 sharp 15.05565343 0.931022901 sony 381.3942184 0.035803627

5. ## Re: A problem of several dummies in regression(Excel)

Thank you!!! but still i made columns for sharp and sony (1 or 0)and put into x input of excel data regression analysis 3 columns: sharp, sony and screen, in y input : price

i got only x1 and x2 after intersection cofficient. that is strange.

6. ## Re: A problem of several dummies in regression(Excel)

Originally Posted by Lisa1992
Thank you!!! but still i made columns for sharp and sony (1 or 0)and put into x input of excel data regression analysis 3 columns: sharp, sony and screen, in y input : price

i got only x1 and x2 after intersection cofficient. that is strange.
Well... I can't see what you have done...
I do know that in your current sheet, the relevant columns are not adjacent, which they have to be.

### includ the manufacturer in a multiple linear regression analysis using a "dummy" variable. does it appear that some manufacturers can command a premium price?

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