Hi, I try to calculate condition indexes and variance decomposition proportions in order to test for collinearity using colldiag() in perturb package, I got a large index and two variables with large variance decomposition proportions,but one of them is constant item.I also checked the VIF for that variable, the value is small.The result is as follows: Index intercept V1 V2 163.54 0.97 0.81 0.16 VIF(V1)=1.4 V1,V2 are two variables with largest variance decomposition proportions. I haven't got the Belsley's book, and don't quite understand what's the meaning of collinearity between intercept and one variable.If that's the case, how to deal with it? Discard the V1 variable? Anyone can give me some suggestions?Thanks -- View this message in context: http://r.789695.n4.nabble.com/Problem-about-collinearity-diagnosis-tp4523096p4523096.html Sent from the R help mailing list archive at Nabble.com.