[Oof Arted]

Seems to be just another waste of time and money

[SimonFa]

I've been playing for about 18 months and play at 3 clubs with a number of partners and am quite pleased to see my grade is a a shade over 50%.

Interesting, after about 100 GIB MP tourney's my average is also a shade over 50%.

[gnasher]

Oof Arted, on 2012-March-10, 10:09, said:

Seems to be just another waste of time and money

That remains to be seen. If it gives people another reason to play more face-to-face bridge, that's a good thing. If it encourages them to play better, that's a good thing too. Those benefits may not materialise, or they may turn out to be insufficient to justify the cost, but I think it's premature to assume this.

There have been several posts pointing out flaws in the system. I don't think it matters that it won't work perfectly - for differentiating good players from bad, it's a vast improvement on masterpoints. For players near the top, we can continue to assess them by asking the question "What has he won?" (This would, by the way, give a quick, easy and correct answer to the question mentioned in awm's final paragraph.)

I can think of one diasdvantage of this scheme: some people may not like being told that they're not very good. However, I doubt if that would cause many people to stop playing: either they'll see it as a reason to try to improve, or they'll dismiss the grading system as being inaccurate, irrelevant, and not nearly as meaningful as masterpoints.

[mr1303]

I come in at 62. something % (but strangely only if I search for myself, rather than search down the list of top players). This is strange, since apart from my last two games which I've played down in Cornwall after I moved here, 99% of all my games in the last 3 years have been with the same partner in a rather low ability club near Bristol. And when I search for her ranking, I'm an ace of clubs, whereas she's an 8.

I think that it needs a little work before it becomes particularly meaningful, but it's a nice idea.

[IanPayn]

mr1303, on 2012-March-10, 14:34, said:

I come in at 62. something % (but strangely only if I search for myself, rather than search down the list of top players). This is strange, since apart from my last two games which I've played down in Cornwall after I moved here, 99% of all my games in the last 3 years have been with the same partner in a rather low ability club near Bristol. And when I search for her ranking, I'm an ace of clubs, whereas she's an 8.

I think that it needs a little work before it becomes particularly meaningful, but it's a nice idea.

++++I agree that it might need a bit of work, but despite my absolute lack of interest in any form of ranking on a personal level, I can see that this is an improvement on "Master Points". It's the difference between a Form Guide and the Dictionary of National Biography. If anyone cares, I'm chairman of the EBU's Tournament Committee, and so I sort-of have a vested interest in this working. But that's wearing my business hat: wearing my other hat, as a part-time member of the human race, I think this is A Good Thing and already stimulating interest. Why, only today someone talking to me declared himself a Queen.

It took a moment...

[Vampyr]

mr1303, on 2012-March-10, 14:34, said:

in a rather low ability club near Bristol.

I imagine that clubs (along with all subsets of the population) were all assigned a 50% average, and that that hasn't moved much.

[blackshoe]

Sure the tactic is available. It's just not nearly as effective.

[mchristie]

I'm Mike, the team leader for the NGS and have just found this thread. Interesting comments. I'll try to give some answers.
1) Andy Bowles now restored to grade of 60+.
2) Grade accuracy standard error of at best 2%, but you need a good mix of partners, and see below for caveats.
3) Biggest limitation: Ann usually plays with Bob and they score 50% (v average opps), but occasionally Bob plays with Dave and they score 45%? Who's the strong player? No grading system can know. NGS will (remarkably quickly) decide that Ann is the strongest getting a grade probably near 55 (but depends on starting conditions). From our unpublished analysis of playing patterns, we think this and similar problems significantly affect the grade of between 2 and 5% of the EBU 50,000 members. (based on Yorkshire test bleow)
4) We have lots of unpublished maths behind the NGS, for example:
test of more complex estimation(Kalman filters/Least Squares estimatation) for the 4000 Yorkshire members over six months, which would give each player a personal grade accuracy as well as grade, but we rejected as it means your grade would change when you don't play, and takes very much more computation.
measures of degree of mixing between clubs (around 50 clubs are sufficiently isolated that it will take over 5 years for their grades to be nationally standardised.)
mathematical behaviour of the discrete filter that the NGS system uses.
etc, etc.
5) NGS does use IMP scored pairs events not just MP.
6) Want to use pair-wise scores of teams events sometime in the future, but we need 100% reliable data on which players were which pair for each match of an event.
7) National/Regional events are weighted threefold. Thsi is primarily to assist in standardising grade averages between clubs ("diffusion"), but has the side effect that for strong tournament players, their grade is more dependent on these events than local club duplicate sessions. So I hope that in a couple of years, many strong players will get a more accurate grade, but I agree it would help if we could use at least some team events for such players. Some professional players suffer from the Dave effect (above) more than others.
8) Partnership grades are more meaningful, but players want individual grades. We're trying to improve the way P'ship grades can be displayed and searched.
If anyone is interested, and has maths or software backgroud, we'd welcome some volunteer assistance with improving and monitoring the system. Contact ngsqueries at ebu.co.uk

[WellSpyder]

mchristie, on 2012-March-12, 07:26, said:

5) NGS does use IMP scored pairs events not just MP.

Thanks, Mike, for posting this interesting reply. The above point 5 is the only one on which I still have some doubts. I know that the documentation for the system is clear about doing this, and about how it is done, but I notice from the indivudual session records for what I have played in recently that none of the imp-ed pairs events have any grading information alongside them - and there are actually quite a lot of these on my record since the county I play in holds an imp pairs event every month.

[gordontd]

WellSpyder, on 2012-March-12, 10:39, said:

Thanks, Mike, for posting this interesting reply. The above point 5 is the only one on which I still have some doubts. I know that the documentation for the system is clear about doing this, and about how it is done, but I notice from the indivudual session records for what I have played in recently that none of the imp-ed pairs events have any grading information alongside them - and there are actually quite a lot of these on my record since the county I play in holds an imp pairs event every month.

We have a Cross-IMP pairs at the Young Chelsea every Friday night, and those events all have grading information alongside them. The only event that caused a problem was the Swiss Pairs with IMP scoring, which has already been noted and was apparently the only one of its kind so far submitted (though we are having another on April 1st).

[WellSpyder]

gordontd, on 2012-March-12, 10:49, said:

We have a Cross-IMP pairs at the Young Chelsea every Friday night, and those events all have grading information alongside them. The only event that caused a problem was the Swiss Pairs with IMP scoring, which has already been noted and was apparently the only one of its kind so far submitted (though we are having another on April 1st).

Thanks, Gordon. That does rather tend to reinforce my suspicion that for some reason the Oxfordshire Bridge Association events on the first Tuesday of every month have been omitted from the analysis. Unlike yours, these are Butlered rather than cross-imped ( ), but the system documentation is clear about how these should be handled, too (and no, it's not the same, since as we discussed not long ago on a different thread, these two forms of scoring don't do the same thing - in particular they have different variances).

[MickyB]

WellSpyder, on 2012-March-12, 10:39, said:

I notice from the indivudual session records for what I have played in recently that none of the imp-ed pairs events have any grading information alongside them

There are lots of pairs sessions that don't have grading info alongside in my records, no idea why, but I wouldn't assume the IMP pairs haven't been graded just because the numbers aren't there.

[mr1303]

Quote

I can see that this is an improvement on "Master Points"

Completely 100% agree with this. But if you've been collecting them for years, how do you feel about their devaluation?

[Vampyr]

mchristie, on 2012-March-12, 07:26, said:

5) NGS does use IMP scored pairs events not just MP.

How do you convert the IMPs to percentages? At the YC sometimes +95 is the winning score, sometimes +30. How are these and scores in the middle treated differently/the same?

[gnasher]

Vampyr, on 2012-March-12, 13:44, said:

How do you convert the IMPs to percentages? At the YC sometimes +95 is the winning score, sometimes +30. How are these and scores in the middle treated differently/the same?

Haven't you read the NGS Guide? Search for "Butler Pairs" and "cross-imped pairs".

At Cross-IMPs, a score of +30 over 24 boards is treated as equivalent to about 58%; +90 is worth about 74%. That seems reasonable to me.

[gordontd]

gnasher, on 2012-March-12, 13:58, said:

At Cross-IMPs, a score of +30 over 24 boards is treated as equivalent to about 58%; +90 is worth about 74%. That seems reasonable to me.

That's a little more generous than the YC tables that are used for converting for Ladder purposes. They would give a little over 57% for +30 & a bit over 71% for +90.

[Vampyr]

gnasher, on 2012-March-12, 13:58, said:

At Cross-IMPs, a score of +30 over 24 boards is treated as equivalent to about 58%; +90 is worth about 74%. That seems reasonable to me.

Perhaps. I just feel that there is a difference between scoring +30 IMPs and winning and scoring +30 IMPs and coming in 8th. Maybe they should be treated as the same (excluding prize money!)? Also in the document it says nothing about taking into account the size of the field. Shouldn't this matter?

[gordontd]

Vampyr, on 2012-March-12, 14:45, said:

I just feel that there is a difference between scoring +30 IMPs and winning and scoring +30 IMPs and winning.

I confess the difference escapes me.

[Vampyr]

gordontd, on 2012-March-12, 15:30, said:

I confess the difference escapes me.

LOL Post corrected.

[FrancesHinden]

Vampyr, on 2012-March-12, 14:45, said:

Perhaps. I just feel that there is a difference between scoring +30 IMPs and winning and scoring +30 IMPs and coming in 8th. Maybe they should be treated as the same (excluding prize money!)? Also in the document it says nothing about taking into account the size of the field. Shouldn't this matter?

You mean, just like the difference between scoring 60% at matchpointed pairs and winning and scoring 60% and coming in 8th? The difference still escapes me.