st: VIF and invariant variables or trend

["dora sepour" <dora05@gnet.tn>]

Dear all,
Before estimating the panels data model, i want to detect muliticollinearity 
between x1 and others explanatory variables. using vif, i regress x1 on x2, 
x3,...,xk

My question is: could the explanatory variables x1,x2, ...,xk  invariant 
variables (like geographical distance), trend and dummies?

Thanks in advance for your suggestions,

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