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Simple Overview of Ratings ( PPI)

The Bridge Club Live PPI Scheme

Introduction

Our Past Performance Indicator (PPI) scheme, started in 2002, is a grading scheme and is considered to be one of the best available grading schemes anywhere. The English Bridge Union National Grading Scheme is based upon our PPI scheme.

The PPI scheme calculates a figure based upon your recent results, which are expressed as a percentage, thus giving a way for members to monitor how they are doing on a daily or monthly basis. You may look up your own percentage on your profile and even see your PPI history in graphical form.

The primary purpose for having a scheme is to help players find compatible partners. Games involving partners of vastly different standards tend to be very uneven – an inexperienced player partnering a Grand Master may feel extra pressure, while a Grand Master may find it tedious to see partner make elementary plays.

But also, the PPI scheme provides an approximate indication of the standard of the bridge players you are partnering and opposing.

Definition

The PPI figures represent the percentage scores that a player would expect to average if partnering another player with the same PPI against a field of BCL members of average standard. As PPI's are purely based on past performance, they should be considered only as a rough measure of standard and not taken too seriously.

Other members looking at your profile (and vice versa) may see one of eight symbols:

These "solid" card symbols will show your PPI category and indicate you are "active". (ie: having played AT LEAST 50 rated boards in the last 3 calendar months).

These "shaded" card symbols show your current PPI in the same way but you are 'inactive". (ie: having played LESS THAN 50 rated boards in the last 3 calendar months)

How it works

The formula calculates a PPI figure for each player that, expressed as a percentage, could be described as a handicap (as in golf). We occasionally use this as a handicap or as the basis for 'seeding' in some of our Special Competitions.

Your PPI figure is updated after every event in which you play in any rooms except the Social and Coaching Bridge Rooms, the Special Competitions Rooms and any room with IMP scoring. The update takes place as the event is archived. (The scheme could include IMPed competitions by using a conversion, but there are no plans for such at the present time.)

The calculations take your partner’s and your opponents' PPIs into account as well as how many boards you play in each event. Remember, there is no advantage for higher standard players to play against less experienced players, as in doing so, their results must be much better than the norm in order to get a positive change in their PPI and the formula is designed to take account of differences in standard between all the players at a table.

The range of PPI figures

There are no artificial limits to the PPI figures. The strongest players have PPI figures of 60% or more and intermediate players could have figures of less than 40%, a difference of 20%.

The spread of PPI figures for players tends to form a Normal Distribution with the obvious mean of around 50% and with a Standard Deviation of around 5%.

What this means is that about 68%, over two thirds, of all members will have a PPI between 45% and 55% and about one sixth will have a PPI above 55% and about one sixth will have a PPI below 45%. Two and a quarter percent of all members will have a PPI above a figure of around 60%.

Bridge Club Live displays PPIs of members by way of one of four suit symbols on the profile of each member. This method has consistently been deemed the most popular in survey polls of members.

PPI  

Suit symbol

Over 55%

 Spade

51% to 55%

Heart

46% to 51%

Diamond

Below 46% 

Club

Having selected these bands, it will therefore be found that :

about 16% of members are denoted with Spade symbols

about 25% of members are denoted with Hearts

about 33% of members are denoted with Diamonds

about 26% of members are denoted with Clubs.

 

 

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