Help on OPR and DPR

[Zholl]

Thanks Ed. So my question now is, should I have only based this matrix on the qualifying rounds? If so, I think that may have been my mistake....

[Zholl]

Well, I just tested the numbers again, and they seem to match up with what you have Ed. There is only a very, very slight difference in a number of them, but it is incredibly minuscule (in the ballpark of 10^-14), so it shouldn't affect the numbers in any significant way. I've also figured out how to have excel rank everything, so I'll update the search on my system to include ranks as well as stats, and I'll make a few minor tweaks as well and should have it up here by Sunday.

Did I mention I have nothing better to do right now than to calculate these minuscule differences and make tweaks to the system while I watch recorded tv in the middle of the night?

[Zholl]

Ok, so to clarify one thing before I actually finalize this, low DPR is good, right? Since it's how many points a robot can be expected to contribute to the other team, I'm pretty sure that a low positive is good, a negative better, right? This should be the last question I have, since going through it the only other things I'm not entirely sure how to do I can look up on excel tutorials.

[kirtar]

Originally Posted by Ed Law

Because of the way our matrices are assembled, as long as every team has played at least one match, the matrix is invertable. That is because the diagonal terms are the number of matches that team played, which is why OPR can not be calculated until you have some matches done. Otherwise you will have some zeroes at the diagonal terms and it will make your matrix become singular and can not be inverted.

Ed

Ah that would be it. The matrix in the pdf has a team which has played no matches.

[Zholl]

Lol, yeah, I had that same problem. That's why I had to create a matrix from TBA data. Didn't stop me from running his example 8 different ways though.

Also, tracked down my test matrix for the Shakedown. I've attached it below if you'd like to take a look at what actually generated that data.

Suffield Shakedown Test.xls

[Ed Law]

Originally Posted by Zholl

Lol, yeah, I had that same problem. That's why I had to create a matrix from TBA data. Didn't stop me from running his example 8 different ways though.

Also, tracked down my test matrix for the Shakedown. I've attached it below if you'd like to take a look at what actually generated that data.

Attachment 7645

Hi,

I looked at your spreadsheet Suffield Shakedown Test.xls. I think you assembled your matrix A incorrectly. For example, the diagonal terms represents the number of matches each team played. They should all be 4. Team 126 and Team 181 did not play 9 matches. Also Team 40 never played with Team 173 so that term should be 0 but you have a 2 there. You must have entered the numbers wrong by hand.

I am attaching the matrix A and vector B. You can try it out and see if you get the same OPR number.

I also looked at your spreadsheet Scout_System_beta_v.5.xls. Even though I am already posting a similar one for everyone to us, I would strongly encourage you to continue to develop yours and customize it for your team. You will learn a lot from doing it. If you need any help or have any questions, just let me know and I will do my best to help.

Regards,

Ed Law

[Ed Law]

Originally Posted by Zholl

Perhaps I should ask a different question...
Ok, so if I take, for example, the TBA data from 2008's Suffield Shakedown and create matrix A based on the number of matches each team played on an alliance with each other team and matrix B is the total combined score of each of the alliances team x played on. I then took the inverse of A and found BA^-1. So would this, then, be correct?

Team #     OPR
40            -5.335839956
88            -10.9064837
125          1.874189107
126          20.9022442
173          16.1766485
175          23.76233256
176          13.22479694
177          -28.94649135
178          33.50075682
181          5.801247409
195          7.939442306
228          5.275340498
230          30.37857031
236          24.79561887
348          8.741658516
500          -1.772256265
571          5.296173934
716          4.886654548
839          19.84073344
999          2.339548465
1027        15.69966416
1071        -6.45134427
1099        -3.094166838
1124        14.84119862
1373        13.59377354
1784        17.20806737
1991        -12.38365654
2064        0.156682971
2067        4.862487992
2170        19.44734797

There must be something wrong with your calculation. I put in all the data into my spreadsheet and I got different numbers. I have attached the spreadsheet for your review.

I have been posting 2009 FRC results with OPR and CCWM at the link below.
http://www.chiefdelphi.com/media/papers/2174

Starting from week 3, you can use it during each regional and just press one button to get updated OPR and CCWM information for that regional provided you have internet access. The source code to calculate OPR and CCWM is in there also. I don't invert matrix since it is not necessary. I use Cholesky Decomposition which is included with the source code. If you have any questions, please let me know.

Ed