I try two different sets of predictors $("$x$"$ variables$)$ to predict a time$-$series relationship via a time series regression model. Each set of predictors has $4$ variables $($x$1,$ x$2,$ x$3,$ and x$4$ in model $1....$and x$5,$ x$6,$ x$7,$ and x$8$ in model $2).$

All else equal, if choosing between these two models I should utilize the one which computes: