In November 2010 I wrote a blog about the impact that strength of schedule has on winning in the NCAA Football Bowl Subdivision. What I concluded was that strength of schedule does not have a statistically significant effect on winning percentage in FBS college football. So I thought that now would be a good time to revisit the strength of schedule argument, as this is the time in the season where teams have played a larger proportion of their games against poor performing FBS teams or against FCS teams. Thus this should be the time where schedule strength should have the greatest impact on winning percent. I collected the data for all 125 teams in the NCAA FBS (winning percent, points scored, points surrendered and a measure of strength of schedule) through the third week of the 2013 regular season, since this seems to be a time period for strength of schedule to have the greatest impact on winning percent.
To investigate what the effect of strength of schedule has on NCAA FBS winning percentage, I conducted a statistical analysis using linear regression. The regression just fits a line to the underlying data and estimates the impact and statistical significant (if any) of the independent variables on the dependent variable. For our purposes, the dependent variable is winning percentage and the independent variables are points scored, points surrendered and strength of schedule.
The results are that points scored is positive and statistically significant (has a statistical impact with at least a 95% level of confidence), that points surrendered is negative and statistically significant, and that strength of schedule is statistically no different from zero using a 95% confidence level. I have also adjusted for heteroskedasticity (unequal scatter in the data) and adjusted for the different FBS conferences and in each case the overall conclusion remains the same.
In other words, for the "league" as a whole schedule strength does not affect whether teams win or lose. Another way of thinking about this is that high quality teams win against high quality opponents and low quality opponents and low quality opponents lose to both high quality and low quality opponents on average. This schedule strength issue seems to be a reason to discount the performance of "inferior" teams - think Boise State and Utah a few years ago or most likely Louisville this season. Yet while this may be a prevailing attitude among many college football fans, especially fans of the "high class" conferences - this perception does not hold up to statistical scrutiny.