I've written about a type of pairing I call a strength-of-schedule pairing. The basic idea is that a team that has had a weak schedule so far (measured by opp. wins, opp. speaks, etc.) gets a strong opponent for the next round. (Of course, all of this is within a bracket, so weak and strong are relative to the average team strength and schedule strength in that bracket.) It sounds simple enough, but it has to work both ways -- both teams get the opponent they deserve in each other.
It hit me how to help people visualize how this pairing method differs from the traditional. First, picture a Cartesian grid, depicting one bracket, like so:
A position along the x-axis shows a team's strength (say, speaker points) above or below the average, 0, of the bracket. (If it helps, you can think of these as standard deviations above or below the mean; or, you can think of these as speaker points above or below 28.) A position along the y-axis shows a difficulty of a team's schedule above or below the average. Quadrant I contains the good teams in the bracket that have had tough schedules; quadrant IV contains the good teams that have had easy schedules.
Ideally, you want debaters from quadrant I (strong teams, strong schedules) to face debaters from quadrant III (weak teams, weak schedules), debaters from quadrant II (weak teams, strong schedules) to face each other, and debaters from quadrant IV (strong teams, weak schedules) to face each other -- to even everything out. Let's look at how the two traditional methods fare. I generated 16 random points on the grid, and based on their scores, power-matched them using these two methods.
The best team faces the second best; third, the fourth; on down to the second worst facing the worst. Two debates are matched between quadrants I and IV. These are unfair to quadrant I teams, who are good teams, with tough schedules, facing yet another good team. There are four debates between quadrant II and III. These are unfair to quadrant III teams, who are weak teams, with easy schedules, facing yet another weak team. I'd say there's really only one good match: the quadrant IV team to the other quadrant IV team. All in all, many of these debates are likely to exacerbate the range of schedule strength teams face. Score: 1/8.
Second, let's look at the high-low pairing method, using the same 16 points:
The best team debates the lowest, then the second best debates the second worst, and so on. This is not much of an improvement in terms of equalizing schedule strength. There are two debates between quadrant I to II -- unfair to quadrant II teams, weak teams, tough schedules, facing another good opponent. There are two debates between quadrant III and IV -- unfair to quadrant IV teams, good teams, easy schedules, facing another weak opponent. And there are two that are truly wretched: quadrant II (weak teams, tough schedules) to quadrant IV (strong teams, easy schedules) -- unfair to both quadrant II and IV teams!! There are really only two good matches, between quadrant I and III teams. Score: 2/8.
Here's what a strength-of-schedule pairing looks like, for the same points:
I didn't tweak it! This is what came out of my algorithm. All eight matches accord with the preferences I spelled out: Is debate IIIs, IIs debate IIs, and IVs debate IVs. I added in the dotted line to show that most of them have this rough symmetry, where the x score of one is nearly as possible -y of the other, and vice versa. Given the random distribution of the points, it's pretty darn good. All in all, this will equalize as much as possible the schedule strength faced by each team in this bracket. Tough schedule? Weak opponent. Easy schedule? Strong opponent. Score: 8/8.