I'd like to expand on the Relative Performance index for those who are not familiar with it.
RPI normalizes the playing field so every team can be compared relative to the competition they've played.
You can find this table towards the top of each NCAAF individual game projection -
e.g. Wisconsin vs Iowa
Wisconsin scores +2.9 points more than their opponents allow on average and they allow -18.1 points less than their opponents score on average.
Iowa Scores +1.5 points points more than their opponents allow on average and allow -3.4 points less than their opponents score on average.
On average, Wisconsin Scores +25.2 pts and allows 15.2 pts
Iowa Scores 32.5 and allows 18.5
what does all this mean? well, we can use the RPI metrics and with each teams actual score/allow to arrive at a projected score, and thus a projected spread.
This is also calculated for Yards/Pt, Yards/Play, Net Yards/Pass, Yards/Run