Dr Ian Plummer

http://www.oxfordcroquet.com/rank/calctbl.asp
Oxford Croquet

This page generates tables which allow you to calculate your ranking index by looking up the number which will be added or subtracted from your current ranking index. It is applicable to National or World rankings.  Note that there is a page which does this calculation automatically.  The tables however can be printed out and used 'in the field'.

You will be able to calculate your instantaneous ranking index but not however your position as you will not have sufficient information. This page can be saved to your local hard disk and run without being connected to the Internet. Press the shift key and click here to save a copy. The details of the calculation can be found in the Techincal Section of this site.

Using the Tables

The generation of the tables is dealt with after these instructions.

1. Calculate the difference in ranking index between yourself and your opponent

idiff is the difference between your opponent's ranking index and your index.

You will get a positive number if your opponent is better than you according to the rankings.

2.  Choose the importance of the tournament you are playing in

The class factor is the importance of the tournament:

class factor = 6 for the Opens, Mens, Internationals
class factor = 5 most tournaments
class factor = 4 consolation events

3. Look up the number of index points you gain or lose

Once you know idiff you can look up how many index points you win or lose under the appropriate class factor column. There are positive and negative rows for each idiff, note that the two values they give add up to 10 times the class factor.

• If you are the initially better player and win (idiff was negative) you gain the smaller number to your index (opposite minus idiff) and your opponents loses that same amount.
• If you are the initially worse player and win (idiff was positive) you add the larger number to your index (opposite positive idiff) and your opponents loses that same amount.

Your ranking grade is a running smoothed average and cannot be calculated from a lookup table, note that there is a page which does this calculation automatically

Table Generation

The following form allows you to generate the index change tables. Please enter the maximum value of idiff and the interval between idiff values: