[FRC Blog] "Standard District Points System for 2015"
 

Blog Date: Tuesday, February 3, 2015 - 15:01

Re: [FRC Blog] "Standard District Points System for 2015"
 

Here's the equation for input into Wolfram:

erf^-1((N-2(R)+2)/(1.07*N))*10/erf^-1(1/1.07)+12

Re: [FRC Blog] "Standard District Points System for 2015"
 

So much for something uniform and easy to understand.

Re: [FRC Blog] "Standard District Points System for 2015"
 

While this is pretty confusing at first glance(and second and third probably), for a given event size the point values are predetermined for each rank. So, the equation can be used to generate all the values for each event, and everyone can just look at a nice simple chart.

Re: [FRC Blog] "Standard District Points System for 2015"
 

It's a little confusing at first, but it's really not that complicated when you understand what is happening.

Kinda best way to simplify it down is it's like when a professor decides to grade on a bell curve. Same concept, just a little more complicated equation to work with the data parameters FRC requires.

Re: [FRC Blog] "Standard District Points System for 2015"
 

Wow. That took a few reads to understand. It's almost like they're trying to make it difficult.

I laughed a little bit while reading some categories, like "Teams on Alliances Advancing Playoff Level" (sounds like it's missing a word) or "Alliance Selection Results After Alliance Selection is Complete". These names seem very complicated and over-descriptive for what they describe.

Also, the use of the inverse error function is just ridiculous. It doesn't need to be this complicated! I'd rather just have a table of values that I can look up, or a much simpler, way more understandable polynomial function that approximates the function in the document.

A requirement for game design is easy to understand and explain. The inverse error function is neither simple nor easy to understand. Most high school students have no clue what it is, so why has it been chosen?

At what point is it unreasonably late for FIRST to release the criteria that will be used to determine a team's advancement to the next level of competition? Honest question here- there's no deadline, and they don't seem to be in any rush to give us information. It doesn't seem unreasonable to think that Michigan teams will be competing before their point system is established!

Re: [FRC Blog] "Standard District Points System for 2015"
 

First takeaway: Why was the QS capped at 22 pts instead of the previous 24? Also, why is the minimum 4 instead of 0?

Not that it matters, but it does strike me as odd.


So max pts this year is now 83 w/ Chairman's, 73 w/out at District events, instead of 85/75.

Re: [FRC Blog] "Standard District Points System for 2015"
 

This is the backend. Yes, teams can look at it, but realistically I'd anticipate most will just be looking at the chart for their event size and not worrying about the math behind it.

Would it have been nice to see at least that points would be based on rank earlier? Yes. But lacking knowledge of the timeline and how much effort went into this, I'm very reluctant to claim FIRST should have done anything differently.

A question for Districts teams: If you had this information at the beginning of the season, would it have changed your strategy for this year's game?

Re: [FRC Blog] "Standard District Points System for 2015"
 

Here is a quick calculation script I threw together. It requires Python 3. The inverf implementation is not mine and comes from here: http://johnkerl.org/python/normal_m.py.txt

I might extend it to generate tables in the future, but it works well enough for now. Let me know if you find a problem with it. It is a .txt because CD doesn't allow .py files.

Re: [FRC Blog] "Standard District Points System for 2015"
 

The answer to the first question is because, even in a WLT system, perfect 24s are pretty rare. In MAR, according to this, 23's have only been done twice, and in theory a 24 should have only happened once at this point. (Though it would be interesting to see what a difference a WLT would have on this game on the rankings). More matches per team make it harder to score a perfect record.

And regardless of the reason for the upper cap, the lower cap probably exists to keep the average score at 12. If the average score from qualifying becomes less than 12, teams that win judged awards, eliminations, or are a new to gain a slightly greater advantage in their 5 or 10 points, and re-adjusting the point values in that respect would make the system even more complicated.

Re: [FRC Blog] "Standard District Points System for 2015"
 

Here's a spreadsheet that uses an approximation method of InvERF(). It's not 100%, kind of a hack actually, so let me know if you have any improvements.

Re: [FRC Blog] "Standard District Points System for 2015"
 

Agreed.

What, you mean like in Frank's Blog on Kickoff Day?

http://www.usfirst.org/roboticsprogr...ct-points-2015

Re: [FRC Blog] "Standard District Points System for 2015"
 

This Wolfram Alpha Widget: http://www.wolframalpha.com/widgets/...2fb3bb85e071b4 should calculate it if I put in all the equations properly (I'm not sure if I completely understand how the district ranking works, so there may be errors). It doesn't require any other programs to run (I know some students who don't have Excel so I decided not to try and figure out the equations in it). Please let me know if you catch any problems in it and I'll try to fix them.

Re: [FRC Blog] "Standard District Points System for 2015"
 

You both forgot the Ceiling Function.

Re: [FRC Blog] "Standard District Points System for 2015"
 

So I just did this for us, but it seems like this would be a small net increase for the teams at the top of the rankings. We went 11-1-0, and 10-2-0, and 10-2-0, with a 1 seed, 1 seed, and 3 seed. So we got 22, 20, and 60, for a total 102. With this structure, we would have gotten 22, 22, and 63, for a total of 107. So if you were constantly at the top seeds, this most likely will be a net increase in points, especially at tougher events, where the 1 seed might only have had 10 wins. However, the top teams are not usually the ones where 5 points makes a difference, so it most likely would not have much of an actual effect on the top.

Re: [FRC Blog] "Standard District Points System for 2015"
 

Thanks for the catch--I believe it's fixed now, but I don't know what the results should look like, so I can't really check. Please let me know if you catch anything else.

The same link should work: http://www.wolframalpha.com/widgets/...2fb3bb85e071b4

Re: [FRC Blog] "Standard District Points System for 2015"
 

Thanks for catching that. Like I said, I'm not in a region with districts, so I tend to miss some of this stuff. Frankly given that, I'm even more confused by some of the complaints in this thread.

Re: [FRC Blog] "Standard District Points System for 2015"
 

In the GameSense interview, Frank mentioned that only 0.6% of all teams scored 24 points last year. I guess it would have been nice to have a perfect comparison to last year, but ignoring the 0.6% doesn't seem devastating to me.

In the summary document, it says "typically-sized district events" would have a minimum of 4 points. Though, in the explanation document the tables show that at about an event size of 55 the minimum goes from 4 to 3. Using Rachel Lim's district points widget, it looks like 3 is the minimum going all the way up to a tournament size of 1,000. If you look at the explanation document, the range scale in the formula is 10, but the gain factor at the end is 12; that says to me the formula is built to never go below 2 points, and because of the nature of the Inverse Error Function (going to infinity at the limits and all) and the use of the Ceiling function, you will never go below 3 points period.

Though, I must admit, it would be a crushing blow for a team to show up at an event and get no points whatsoever. Even if they don't have aspirations of making it to the District Championships, getting a goose-egg is deflating.

Re: [FRC Blog] "Standard District Points System for 2015"
 

I think a one sentence version of Danny's white paper should really ought to go into the manual with a graph (and a link to the white paper!). This function is going to be needed to be explained several thousand times this season and teams/volunteers/the public seeing math as a scary black box is good for no one.

Something along the lines of "This function assumes teams are approximately normally distributed, and awards points based on rank. The #1 seed will receive 22 points, the middle of the pack ~12, and the lowest ranked teams ~4.

Then a plot for a 40 team event, with rank on the x axis and points awarded on the y.

Re: [FRC Blog] "Standard District Points System for 2015"
 

To clarify, 23's have only been done twice. 22's are a little more common.


Oh, and I made a spreadsheet showing how the QS points will be distributed by rank for every MAR event. The MAR events are all similar in size this year, so it doesn't change much event by event.

Re: [FRC Blog] "Standard District Points System for 2015"
 

Really? You think Volunteers and the Public care about the District Points System beyond what can be found in a, "Rank/Points" chart?

I'm glad FIRST didn't just publish a "bunch of tables" and actually showed us what's behind the scenes. It gives more credibility to the data in my opinion.

Re: [FRC Blog] "Standard District Points System for 2015"
 

This is the key point (pun intended) in the discussion^*
The small difference in points for teams at the top and bottom of the distribution make little impact on progression through the season. For example, in New England last year every team with a record of better than 10-2-0 at either of their scored events ranked in the top 10 teams going into the District Championship.

However running the 2015 rank-based points model on 2014 New England results shows that there would have been only 1 change to the teams invited to the District Championship. So it doesn't seem to make much difference in the middle of the pack either.

One small effect of the change is that teams are no longer penalized directly for disqualification or not being inspected in time for the qualifications matches. The indirect penalty of a reduction in average score may be larger.

Finally the use of the ceiling function means smaller events have a slightly higher expected points total per team, but this is minuscule in comparison to the huge seeding/playoff points advantage at smaller events.

^*although I personally enjoy any work incorporating a statistical model, so props to Danny!

Re: [FRC Blog] "Standard District Points System for 2015"
 

I've turned the output of this program into a series of tables. Each file in the archive corresponds to an event size, and in each file each line lists a ranking and the number of points that is.

A quick note on the script: I have not verified the script and the first line of it says to use python 2.7 rather than version 3, so perhaps take these numbers with a grain of salt.

Re: [FRC Blog] "Standard District Points System for 2015"
 

We're confirmed to enter the District System next year (NC) so I'm trying to understand the math now. After the explanations of the formula - I get that...but I'm not sure I get how the Alliance Captains and Draft Order points compare. Would the first alliance captain and their first pick both get 16 points?

Re: [FRC Blog] "Standard District Points System for 2015"
 

What better peer recognition could there be than being the #1 choice of the top ranked team?

Re: [FRC Blog] "Standard District Points System for 2015"
 

I love math.
:cool:

Re: [FRC Blog] "Standard District Points System for 2015"
 

Yes, Alliance Captain 1 and their first pick both get 16 points, #2 each get 15 ... down to #8 captain and pick both get 9 points.

Alliance Captains are based on the position they hold after picking is done (e.g. if #1 picks #2, the original #3 captain becomes alliance captain #2 and gains a point).

Then on the way back up the serpentine draft, 2nd pick (3rd alliance members) for alliance #8 gets 8 points, #7 gets 7 points ... #1 alliance (last pick) gets 1 point.