Week 4 OPR

[Navid Shafa]

Originally Posted by Ed Law

Your team is ranked 29 out of 1548 teams who have competed so far. That is very good. You are one of the better teams.

WOW. That is truly astonishing, I knew there was going to be some strong competitors popping up from the Midwest regional, as I recognized some of the Alamo powerhouses...

I want to thank everybody for following up on this thread, filling in my holes and painting a clear picture of the current world standings.

Ed: I was just talking to a team-mate about this exact database yesterday. I remembered using it in 2008 and 2009, but I forgot who made it and where to find it. I'm glad that I have access to it once again.

I am extremely excited for St. Louis and I figure that with a strong alliance we could go far this year!

Thanks for all your input and advice!

[mwtidd]

Originally Posted by Ed Law

Nathan, this has already been done by Team 33. But it was done manually as a one time thing. The data looks interesting. I was going to automate that using the twitter feed but when I heard that there are missing matches and may be even event, I changed my mind. I don't want to spend time on something if the data is not reliable. If anyone is interested in pursuing that, you are welcome to modify my macros. All the macros in my spreadsheet are not protected. It includes all code needed to assemble and solve the matrix for you.

Nathan was asking about ETC, ERC and EMC which have nothing to do with matrices or OPR. And they are all calculated automatically. I just haven't published the latest version of my site.

Originally Posted by Nathan Streeter

Lineskier (Mike?), would it be possible to use the matrices to compute the EMC and ERC? I really like that EMC and ERC use the twitter feeds to break down a Robot's contribution into Minibot and Hostbot, but without the matrices, they just don't have the same accuracy.

Actually matrices inherently has an equal potential of inaccuracy. Digging through my threads I talk about how my algorithm is actually executed and the resolution it gets over OPR. Matrix algebra looks at the big picture, but it doesn't look match to match. ETC does look match to match. Point inflation affects both in different ways. Also I can tell which alliances finished in which place with minibots. So if someone has an EMC of 30 I KNOW in every qualifying match their alliance put up a winning minibot.

Also I calculate your team's contribution to each match, for the robot. OPR does as good a job as it can using traditional mathematics. I use CS algorithms to calculate my #'s. That being said there are still issues with point inflation that are inherent in any system. Some teams will have the luck of the draw. I have an idea of how to fix this for the ERC but it will take a bit to implement.

If someone had a java function for calculating OPR I could quickly implement it. ETC and OPR look at a teams contribution from 2 separate directions. I believe by utilizing both that the values it will hone in on a team's true contribution.

[Ed Law]

Originally Posted by lineskier

OPR has actually the product of collaborative work done by many individuals who are still on CD ( I know Jim Zondag worked on it, and he is still very active in the CD community)

The origin of OPR was not a collaborative effort. I was talking about who coined the term and first proposed it. From what I can find, it was Scott Weingart from Team 293 in this post dated 4/6/2006, http://www.chiefdelphi.com/forums/sh...0&postcount=19. He is no longer active on CD as his last post was 4/13/2007.
I was not talking about who use it. Many people use it as a supplement to match scouting. Yes it is very simple matrix algebra and many have written their own programs to calculate it. If implemented correctly, the OPR numbers for each regional/district should be identical.

I am glad to see you proposing a new way of ranking teams. I always welcome innovation. However I do have serious concern about your method. This is not a personal attack so please don't be defensive. I just want to point out a few things so you can improve your algorithm if you choose to. I am not saying OPR is better. I am not defending OPR as I don't own it. In the end, you look at how numbers are calculated and you choose what you think will work for you.

1) One of my concern is if a team has a bad first match for whatever reason and that team's alliance score zero points. Then the next time this team play, according to your algorithm, you will assume that this team does not contribute much to whatever the score was for their second match. Please correct me if I misunderstood your algorithm.
2) I also read someone suggested to you that it should be iterative, i.e. loop back and have a second pass and third pass etc. I don't know if you tried this or not. An iterative method is fine as long as it converges. If it diverge or oscillate, then there is something wrong. In your method, does it always converge and if yes how many iterations typically before it converges. Have you compared the converged value to OPR? Are they close to each other?
3)One of the point you advocate about your method was considering match to match effect rather than a big picture like OPR. When you iterate, it is no longer just match to match. This is somewhat analogous to finite difference method. You are actually getting the effect of all the matches when you loop back and iterate.
4) If you argue that it should not iterate, then the final number is too dependent on your starting value and the method will not be mathematically valid.
I hope you will find a way to improve it so we will all benefit from a better way to rank teams.

[IKE]

Originally Posted by Ed Law

Nathan, this has already been done by Team 33. But it was done manually as a one time thing. The data looks interesting. .

When compairing this data to some scouting data, it was reasonably accurrate. It turned into a bit of a "tube scoring" version of OPR. I have also eseen this done with penalty data, and some other interesting factors. We should have some good scouting data from Troy that hopefully we can use to tune the algorithms to be even more representative, and then test them at the State championship.

Like the robot, iterating and progressively improving your scouting and metric based scouting as the season continues helps a bunch.

[dcherba]

I have written a html screen scrape that collects seeding data from all the regionals. Just raw data for all of you to play with. It beats copy and paste from all the web screens. It is interesting to note that there are three different styles used on the web displays. I would have thought all the web scripts would be the same..

DMC Mentor team 3234