What are Relative Performance Ratios?

One of the principal problems with evaluating statistics for collegiate  sports is that the teams play such varying schedules. As a result, one can never  be sure whether a stat represents a team's performance, or simply reflects the  quality of its schedule. "Relative Performance Ratios", or "RPRs", are an  attempt to solve this problem by comparing what a given team has done to what  its opponents have collectively allowed in other games.

For example, if a team's offensive "Yards per Rush" RPR is 1.15, it means  that team has rushed for 15% more yardage on each attempt than its opponents  have allowed in their other games. Similarly, if a team's defensive "Yards per  Pass Attempt" RPR is .85, it means the team has held its opponents' passes to 15% less yardage per attempt than those opponents have gained in their other games.

This system has clear limitations. It assumes that each team's opponents'  opponents are of roughly the same quality, which is often not true. Two teams'  opponents' opponents do, however, tend to be much more similar than the teams'  opponents, simply because there are more of them. After week 5 of the season,  for example, most teams will have played 4 opponents; those opponents will have played 12 other teams. Overall, I think RPRs can be a valuable tool in assessing  the relative strengths of college teams. They provide an objective basis for subjective analysis of teams' performance.

The best way to view these tables is to open them directly in a spreadsheet program such as Lotus 123 (which was used to create them), Microsoft  Excel or Quattro Pro. That allows the tables to be sorted using the spreadsheet's functions.



Using RPRs and the basic stats published by the NCAA, I prepare projections  of each week's Pac 12 games. These are NOT predictions of what will happen, but  are instead straight algebraic extrapolations of what would happen if (IF!!!)  both teams were to play as they have, on average, in earlier games. That "IF" is  crucial, because teams never play exactly as they have before. These projections  make no attempt to evaluate morale, injuries or the teams' game to game  improvement. If these aren't predictions one can take to one's bookie, what good  are they? I use them as an objective basis for further subjective analysis of a  game, and in that role, they serve quite well.


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