You have an error in your use of the interaction idea. See the attached Google search or Montgomery Design and Analysis of Experiments in the z-library. Best wishes, David Booth

David Eugene Booth Thank you for your response, If i understand it correctly, you propose to adjust the interaction term in the dependent variable to the simple DV without interaction.

And also to use Czech as an independent variable, am I right?

Hello Martina Kopová. Why are you multiplying DV by Czech? The result will be either 0 or 1 for each individual.

I have several other questions:

Thanks for clarifying.

Thank you Bruce Weaver

1. The DV is post-purchase intention

2. explanatory variables: IDV, MAS indexes (cultural characteristics), factor scores (referencing to customer preference), perception of a certain brand

3. I wish to compare all of them between the Czech and Dutch respondents

4. sample size is 300, 150 of Czech and 150 of Dutch respondents (merged into one data set) to be able to use one regression

I also have control variables such as age, education, female and two income groups

In DV = b0 + b1*Czech, b0 is the mean of DV for Dutch, and b1 is the mean difference in DV between Czech and Dutch.

Czech*DV on the left-hand side of your equation makes no sense. Theother terms (b2*Czech, b3*Czech,...) make no sense either. This whole part of your right-hand side could be written as b0 + (b1+b2+b3+...)*Czech, and the sum of the coefficients can be (andmust be) treated as a single model coefficient (i.e. as the mean difference in the DV between Dutch and Czech.

An interaction would be modelled between two difference predictors by their product. In your example I see only Czech being a predictor. Another one might be, say, Age. Then the model

DV = b0 + b1*Czech + b2*Age + b3*(Czech*Age)

would be a model where:

b0 is the mean DV of Dutch at age 0,

b1 is the mean difference between Czech and Dutch at age 0,

b2 is the mean change in the DV per year of age for Dutch, and

b3 is the interaction of Czech and Age, i.e. the difference in the mean change per year between Czech and Dutch.

In this example, the coefficients b0-b2 are not particularily usefulpractically, but required by the model to estimate the inteaction. If the Variable Age is centered at age a, then b0 and b1 would refer tosubjects at age a.

Jochen Wilhelm firstly, Thank you for your great advice!

To confirm that i understand it properly, you’re advising to use:

(I added some other explanatory variables from my model)

DV = b0 + b1Age + b2Perception + b3GreenPreferences +b4Czech + b5Age*Czech + b6Perception*Czech +b7GreenPreference*Czech +error

Do I inderstand it correctly? If not please correct me.

Thank you again for your help!

Jochen Wilhelm might be busy watching football right now (Czech Republic v Denmark, as it happens), as I am about to do myself! ;-) But yes, you have understood his advice correctly. And as you are using SPSS, note that if you use the REGRESSION command, you will have to compute all of those product terms as new variables in the dataset. You can avoid that task by using UNIANOVA (or equivalently GLM) to estimate your model. UNIANOVA allows you to specify product terms on the DESIGN sub-command. For the model you specified, for example:

UNIANOVA DV WITH Age Perception GreenPreferences Czech

/PRINT PARAMETER

/DESIGN=Age Perception GreenPreferences Czech

Age*Czech Perception*Czech GreenPreference*Czech

.

The output from the PRINT PARAMETER line will show you a table of coefficients.

HTH.

Hahah Bruce Weaver I’m also busy watching. Thank you for your clarification! It helped me so much

Jochen Wilhelm provided an excellent answer for meaning of coefficients. Bruce Weaver also provided an excellent syntax in SPSS. Nothing to say more for their comments in your situation.

If you need more information Lesa Hoffman also provided an excellent explanation about them.

https://www.lesahoffman.com/PSQF6242/index.html

You have to check Lecture 6 and Lecture 7.

hello dear

You can find the answer from this paper

Thank you Teshita, this paper’s helped me a lot!