Re: Multicollinearity in SPSS

Posted by Almost Done on Aug 06, 2012; 9:24pm
URL: http://spssx-discussion.165.s1.nabble.com/Multicollinearity-in-SPSS-tp1070043p5714600.html

Hey, guys! I might have a problem that might seem easy to you but it isn't for me. I'm doing a research about creative advertising and have to check for example whether the divergence (rated on a seven point Lickert scale) and relevance (rated the same) and the interaction between the two divergence*relevance has an effect on the attention that the respondents also rated on a 7 point lickert schale. So when I run a regression this is what I get:

                                               B             t                    sig
Constant                                 ,529         ,649 ,518
Divergence                              ,666         4,215            ,000  
Relevance                                ,573         2,275            ,024
Divergence*Relevance              -,091        -2,012           ,046

This seemed weird to me because divergence*relevance has a negative influence on the dependent variable attention. How can it be?
So I removed the Divergence*Relevance interaction, and this is what I got:

                                              B                 t              sig.
Constant                              1,892            4,113        ,000
Divergence                            ,398             4,622        ,000
Relevance                              ,090              1,167       ,245

So the B and significance changed drastically. I've tested for multicoliniarity using the VIF. The combination where the Divergence was the dependent variable (and independent : Divergence and Divergence*Relevance) was the one where VIF was greater than 5. All the other combinations were fine (VIF was either 1 or slighter greater than 1).

So my question is - what does that mean and how do I proceed? What do I have to do? And how should I explain that?