With 1:46 remaining in the second quarter, Penn State faced a 4th-and-1 from the Ohio State 20 yd. line. Penn State decided to go for it. I think this is completely correct, as outlined below.
If you decide to attempt a FG, Ohio State is guaranteed one more possession. Assuming an 80% success rate for the attempt, trying a FG gives an expectation of 2.4 points, with 1 more possession for Ohio State.
If you decide to go for it, Ohio State will only get one more possession if Penn State fails to get a first down. I have estimated the following probabilities: 40% - failure to get a first down, 10% - get a first down, but do not score before the end of the half, 30% - get a first down, kick a subsequent FG, 20% - get a first down, score a subsequent TD. Going for it results in an expectation of 2.3 points, and an expectation of only 0.4 more possessions for Ohio State.
I've tried to be transparent with my own (subjective) probabilities in case others believe differently and want to do their own calculations. I think it will always be close from an "expected points" point of view, so the difference for me boils down to creating a "turnover" by trying to eliminate one of Ohio State's possessions.