Which Alliances Get Better At Events?
January 17, 2013 • ∞
A rising tide lifts all boats. - Wrongly Attributed to JFK
In the previous article, we found that during the typical Rebound Rumble qualifying event mean alliance scores would increase roughly 50% from the first to final match. While that is impressive, the increase in mean score doesn’t tell us a terribly large amount about which alliances are improving. It could be driven by the the small number of very good alliances getting significantly better, or it might be driven by the middle of the pack getting somewhat better. To see which teams were getting better, we tracked the quartiles (25th percentile, 50th percentile, 75th percentile) over the course of all events. The evolution of the median (50th percentile) is shown below.

We found in the last article that while alliances get significantly better at scoring points, they get only slightly better at avoiding penalties. We assumed that this meant the bottom tier of alliances that is more likely to get penalties didn’t improve over the course of an event. It turns out we were wrong!

The 25th percentile, 50th percentile (median), and 75th percentile alliance all improve dramatically over the course of the event. The 25th percentile alliance got 130% better over a typical event, the 50th percentile alliance improved 70%, and the 75th percentile alliance improved roughly 40%. In absolutes, the 25th percentile alliance scored 6 additional points by alliance selection, the 50th percentile alliance scored 8.5 additional points, and the 75th percentile alliance scored 9 additional points.

Perhaps the most interesting factoid to come out of that is that while the 50% percentile and 75th percentile alliance learned to score the same additional number of points over the course of the match, the 75th percentile alliance showed up to the event capable of scoring an additional 10 points. Interestingly enough if you repeat the exercise for the 80th, 90th, and 95th percentile those alliances also only get roughly 9 points better over the course of the event (but their initial scores increase). We are not sure what causes this – but had you asked us for our prediction we would have gotten this one wrong. Is there a certain level of robot ability that once you break all drivers can reasonably improve? Or are the really top teams in the 90th percentile alliance not improving but their lower scoring partners are? Also worth noting that R^2 starts to drop off above the 80th percentile.

What is R^2? In extremely rough terms it says how well the model fits the data. A number near 1.0 means that you (probably…) have a good fit, a number near 0 means you most likely have a bad one. We highly recommend you take a statistics class (or a couple of them!) to learn how frustratingly complicated the intricacies of this can get. Particularly Econometrics. It was probably the most interesting class I took in college, and I got the nerd cred of learning how to use Stata, which runs the FiveThirtyEight model.
Moral of the story is that if you want your friends and neighbors to come check out “that robot thing”, they will see the highest scoring (and hopefully most fun) matches on the final day of the tournament. And since scores in all quartiles improve as alliances get more practice, we are looking forward to the day that all teams get to play in district style events where they see more matches.
We also think this data shows that most teams benefit significantly from practice. So finish your robots early and practice how to drive ‘em like you stole 'em.
On a totally unrelated note, we would encourage teams that must yell something as they walk through the pits to say 'Rowboat’ instead of 'Robot.’ And maybe people would actually clear out of the way if you were dragging a rowboat on a trailer…
