What do you use to calculate point spreads?
A ranking system that I update weekly based on how far from the expected point difference the results are.
If a score's very close to the expected results, the point value for those teams don't change. If, for example, the result is about 6 points from the expected, I'd add a point to one team and subtract one point from the other.
The math is simple, but it involves tracking every game for the 125+ fbs schools, so it's time consuming.
It's shocking how often my spreads are right on the Vegas lines. I use this to predict line movement during the week.