Commonality analysis of three variables on gasoline efficiency based on adjusted R2 (default) by glmm.hp(), common variance between ‘wt’ and ‘carb’ is a negative value (−0.002).

Jiangshan Lai et al. disscussed the extended functions of glmm.hp package, an R package designed to evaluate the relative importance of collinear predictors within #GeneralizedLinearMixedModels ( #GLMMs ).
doi.org/10.1093/jpe/...