Hello all and thanks in advance for any advice. I would like to calculate the variance inflation factor for a linear model (lm) with 4 explanatory variables. I would then like to use this to calculate QAIC. I have used the function vif() in the car package and I get values for each variable however the equation for QAIC seems to need a single variance inflation factor for the global model. Can I calculate this based upon the output from this function and if so can someone help me understand how? Cheers, G. [[alternative HTML version deleted]]