Big Step Forward for X-Clubs

Bob Fearn, as many will know, is the author of Compass scoring which is the engine powering X-Clubs and, for the last four years, the NZ-Wide Babich Simultaneous Pairs. In 2018 Bob took an interest in scoping out a National Grading System (NGS) for use in New Zealand. An NZB NGS would open up a whole new dimension to our game - handicaps. Bridge players can now go out to beat their handicap not their playmates. This challenge is now available for all players of X-Club deals.

Bob completed this massive project using the X-Clubs data-set as a basis. In effect all players of X-Club hands will earn an X-Clubs rating. Let's call it XG because it's a closed shop based on C-point club bridge played with the same hands - a very different situation from a true NGS which would include both club and tournament results and, for about two thirds of clubs, no comparison based on the same cards being played. This XG system opens the door for NZ bridge to provide large-scale handicapped results.

Calculating the XG involves a huge amount of data crunching which Bob does weekly so that any score changes get incorporated. The method closely parallels the EBU model and involves consideration of your XG, your partner's XG, and the combined XG of your opponents. It builds up over the most recent 2000 boards before old scores begin dropping off. A minimum of 300 boards - about 12 sessions - need to be played before an XG starts to settle down - see the graph below. A basic example of how the calculation is done is attached below. Click to download it.

At present there are no plans to provide an interface to the tabulation but I can tell you .. it looks pretty damn SEXY!! You can export an individual's record to Excel (sample attached below), produce a graph, or export a summary of everyone's standings to Excel .. it even does this as an XML for posting to the web:

Starting from Week 04 a complete summary like this of over 2600 X-Clubbers has been posted along with the weekly Leagues tables.

But .. but .. but - the Main Course: every result Ladder - two per day - will now come with four extra sortable columns - XG Rating, XG Handicap Result, XG Handicap Placing, XG Status. An example:

Just click on any of the green column headers to sort as desired - example

The three categories of XG Status U, E, M are Unpublished (played < 150 boards), Evolving (played between 150 and 1000 boards) and Mature (played > 1000 boards). This is because it takes a while for the XG's to settle down - see graph below as an example. Thus, a reasonable player who is status U has a good chance at coming top on the Handicap as their XG will remain at zero until they get beyond 6-7 sessions.

Remember .. all the columns in the Ladder may be sorted by clicking on the green column headers.

Sample GraphSample Graph

Separate handicapped results ladders are now available.

Non-X-Clubbers .. are you up for battling your handicap? Talk to your committee today about giving X-Clubs a try. It's free. It's easy. Join the 37 other NZ clubs that play the same hands simultaneously every day.

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XG - A practical example.doc32.5 KB
XG Record for 64504 Michael Neels.xls68.5 KB