WBF VP scale changes

[barmar]

A basketball score almost certainly has to be from a very long match.If you have a long match like that and get a score of only 13-2, it means that almost all the boards were pushes, suggesting that the two teams are about equal; that's exactly the opposite of what the high ratio would suggest.

 

A score like 113-102 means that you had lots of swings. But it also means that about the same number of swings went in each direction, which again suggests that the teams are about equal. The increased number of big swings suggests that both teams have some aggressive players.

 

If we're talking about matches of different lengths, then it would probably be appropriate to normalize the VP scale, perhaps dividing IMPs by #boards. The traditional VP scales simply have different scales for different match lengths.

[aguahombre]

On 64 boards, the winner moves on.

[barmar]

Good point. What is the longest match played using VP scoring?

[Rossoneri]

Good point. What is the longest match played using VP scoring?

 

No idea. Probably national trials where there's a small enough pool?

[gnasher]

Good point. What is the longest match played using VP scoring?

The longest I know of is the English Premier League, which has 60-board matches converted to VPs.

[Trinidad]

It seems pretty obvious that he is talking about both teams playing the same # of boards to me.

Then the first sentence of my post is true:

There is no fundamental reason why 113-102 is better or worse than 13-2.

Rik

[mgoetze]

IMO a team that wins 13-2 IMPs should score better than a team that wins 113-102,

Given duplicated boards and matches of equal length, it seems obvious to me that the match which ended 13-2 included better bridge all around than the one which ended 113-102, and thus I would reach the opposite conclusion.

[mycroft]

Given duplicated boards and matches of equal length, it seems obvious to me that the match which ended 13-2 included better bridge all around than the one which ended 113-102, and thus I would reach the opposite conclusion.

That I would agree with, but the match that ended 13-2 may have no better or worse bridge than the one that ended 28-17, if (as I said before) system differences meant that 2 games were played the "wrong way up" by the weak NT openers, one going down because it was wrongway, one making only because it was wrongway. Never mind the partscore issues, that's 22 IMPs on "who's on lead" that, sure, balance themselves out, but aren't going to lead to a 13-2 game.

 

The bridge could be *better* than the 13-2 game, but in the 13-2 game everybody was playing the same system, so the auctions and the contracts were frequently almost identical.

 

Also, my final questions, also above, still apply: do you punish the "high-variance" players when they win (because they tend to win 72-60 over 16 rather than 34-20) and their opponents when they lose (because they tend to lose 72-60, too)? If so, do the losers in the wild match do better because of the bad bridge (required if each match is worth the same number of VPs) or do they get punished, too (which means that wild matches score fewer VPs than low-scoring matches with the same IMP difference)? Whichever way you choose, there are problems.

 

Now, currently, one reason to play a non-standard system is that it's higher-variance; that more total IMPs will be scored than with the "local normal". If you're significantly better than the field, then on average not only will you still win, but you will win by more than if you were playing "local normal" (because your variance wins are wins, and your skill will minimize the variance losses you suffer, in addition to the expected wins by skill difference). That means that it is currently (where just the difference counts) an advantage for those pairs to play something different, over and above the benefits of playing the system. That might not be right, but the counteraction proposed certainly isn't any righter.

[Cascade]

Given duplicated boards and matches of equal length, it seems obvious to me that the match which ended 13-2 included better bridge all around than the one which ended 113-102, and thus I would reach the opposite conclusion.

 

If its better bridge all around do you think that both sides should get better scores?

[mgoetze]

If its better bridge all around do you think that both sides should get better scores?

Nope. (Of course, as mycroft points out, there are other possible reasons for high variance than bad bridge. If it were the only possible explanation, this idea would hold more attraction, but there are still arguments to be made against it.)

[Fluffy]

Given duplicated boards and matches of equal length, it seems obvious to me that the match which ended 13-2 included better bridge all around than the one which ended 113-102, and thus I would reach the opposite conclusion.

Sorry but looks to me you are disageeing with me just because disagreeing with me its natural for you.

 

 

You say 13-2 incluided better bridge, and thats exactly my point, 13-2 involved better bridge and a team got a well deserved victory leaking only 2 IMPs to a strong contender, the 113-102 was just loads of luck all around and something close to a tie is fair.

[mgoetze]

Sorry but looks to me you are disageeing with me just because disagreeing with me its natural for you.

 

 

You say 13-2 incluided better bridge, and thats exactly my point, 13-2 involved better bridge and a team got a well deserved victory leaking only 2 IMPs to a strong contender, the 113-102 was just loads of luck all around and something close to a tie is fair.

No, the point is that you are only looking at it from one point of view. The VPs for the losing teams matter too...

[Hanoi5]

When the 30 VP's scale was in use a bye got 18 VP's, how many VP's are byes getting now? Is this the table which Bali will use? Is there a link to the 'officiality' of this decision?

[jallerton]

As 'Bye' tends to equate to 'average plus', the obvious 'Bye' score on a 20VP scale would be 12VPs.

 

However, that's far too simple and rumour has it that the Committee favours using one third of the cube of Pi.

[fromageGB]

As 'Bye' tends to equate to 'average plus', the obvious 'Bye' score on a 20VP scale would be 12VPs.

 

However, that's far too simple and rumour has it that the Committee favours using one third of the cube of Pi.

I don't see how a bye is worth anything like 12 out of 20. However, it is arguable that you should get more than just an average 10, so I would say a third of the cube of pi is about right.

[aguahombre]

The fact is it doesn't matter one iota how many VP's a team gets for a bye. The only purpose of assigning VP's for the non match is so that when we read the state of a RR before its conclusion, we can figure out the teams' standings without counting the difference in the number of matches they have played.

 

At the end, those artificial VP's could be wiped out without changing anything.

[Fluffy]

you never played a swiss I supose

[gordontd]

I don't see how a bye is worth anything like 12 out of 20.

Currently we give Av+ for half the boards of the match in the EBU - ie 3IMPs per board for four boards of an eight-board match, which translates to 15 on the current EBU scale, would be 14.39 on the new continuous scale, and would be 14 on the new discrete scale. I wonder why you think it should be less than 12?

[gnasher]

Currently we give Av+ for half the boards of the match in the EBU - ie 3IMPs per board for four boards of an eight-board match, which translates to 15 on the current EBU scale, would be 14.39 on the new continuous scale, and would be 14 on the new discrete scale. I wonder why you think it should be less than 12?

If you want to mirror the use of average-pluses in other circumstances, shouldn't the score for a bye depend on the circumstances? If it's unexpected, eg one caused by the opponents' absence, you should give either +3 IMPs per board, or the team's own VP average* for the entire event (both before and after the bye), whichever is higher. If, on the other hand, the bye is a feature of the movement, they should always get their own VP average, ie the equivalent of factoring in a pairs event.

 

I dislike giving people unearned good scores, so if I wrote the rules they'd always get their own VP average. Similarly, in a pairs event I'd score all unplayed boards by factoring.

 

* In a Swiss, arguably the VP average should be adjusted according to their position in the field when the bye occurred. If, for example, you obtained your average when lying 30th, but your bye occurred when you were lying 10th, you don't deserve to receive as much as your own average.

Edited January 27, 2013 by gnasher

[aguahombre]

you never played a swiss I supose

Never played a swiss with byes. When there is an odd number of teams, 3 are thrust into a RR for two matches.

 

Being dropped into a swiss from the mother event is different.

[mgoetze]

I don't see how a bye is worth anything like 12 out of 20. However, it is arguable that you should get more than just an average 10, so I would say a third of the cube of pi is about right.

No, I think a third of the cube of pi is not enough; 4 times Euler's constant would be closer to the mark if you ask me.

[fromageGB]

Currently we give Av+ for half the boards of the match in the EBU - ie 3IMPs per board for four boards of an eight-board match, which translates to 15 on the current EBU scale, would be 14.39 on the new continuous scale, and would be 14 on the new discrete scale. I wonder why you think it should be less than 12?

Gnasher said it well.

 

I remember missing the motorway exit while getting to the Great Northern Swiss Pairs, arriving too late for the first round, and being awarded 10/20 for the starting point on the next round, and this seemed sensible. 12/20 would not be. However, I was actually awarded half(or a quarter) of a green for the missed round (which you would get for a 10/10 draw) which made me think the best way to increase your greens would be to enter for lots of events and not turn up. :D You'd need to be Abramovich, though.

[gordontd]

I remember missing the motorway exit while getting to the Great Northern Swiss Pairs, arriving too late for the first round, and being awarded 10/20 for the starting point on the next round, and this seemed sensible. 12/20 would not be. However, I was actually awarded half(or a quarter) of a green for the missed round (which you would get for a 10/10 draw) which made me think the best way to increase your greens would be to enter for lots of events and not turn up. :D You'd need to be Abramovich, though.

That doesn't sound right to me (on either count). You were directly at fault for not having played the match, so you certainly shouldn't be getting 10 VPs, never mind a quarter green point.

[fromageGB]

That doesn't sound right to me (on either count). You were directly at fault for not having played the match, so you certainly shouldn't be getting 10 VPs, never mind a quarter green point.

I'm sure you weren't directing. But it was a long time ago.

[olien]

If you want to mirror the use of average-pluses in other circumstances, shouldn't the score for a bye depend on the circumstances? If it's unexpected, eg one caused by the opponents' absence, you should give either +3 IMPs per board, or the team's own VP average* for the entire event (both before and after the bye), whichever is higher. If, on the other hand, the bye is a feature of the movement, they should always get their own VP average, ie the equivalent of factoring in a pairs event.

 

I dislike giving people unearned good scores, so if I wrote the rules they'd always get their own VP average. Similarly, in a pairs event I'd score all unplayed boards by factoring.

 

* In a Swiss, arguably the VP average should be adjusted according to their position in the field when the bye occurred. If, for example, you obtained your average when lying 30th, but your bye occurred when you were lying 10th, you don't deserve to receive as much as your own average.

 

Then at which point do you establish an average? Some things could end up skewed: i.e. the tournament favourites may have a more difficult schedule at the beginning which would artificially deflate their average, while a weak team may have an easy schedule at the beginning artificially inflating their average.