(1) The normal Elo system is used, with differences converted into rating change.
(2) To kick start the system, England and Australia were both given ratings of 2500.
(3) To get on the list, the country must have played at least 10 matches, at least one of which must have been a win. (As opposed to scoring at least 1 point.) If it took a country > 10 Tests to win a match, then just the previous 10 results were used to calculate the initial rating.
(4) South Africa and Zimbabwe were treated as unrated when they returned from their bans (for apartheid, and for self-imposed reasons respectively).
(5) k = 25. Why? It seemed to give the best mix between volatility and "accuracy". I looked at when periods of dominance ended (e.g. WI in the 1990s, Australia more recently), and concluded that k = 25 was the best of the 5-point intervals between 0 and 50.
(6) Ratings are live, rather than over a 1-month period.
(7) No account is made for series; e.g. if you're 2-1 down in a series, you would try to win more than you did at the start of the series. This is a bit like chess; in a team environment, you might try to win more than you set out to do, and end up losing instead of drawing, for example.
These are the Test ratings my software spewed out, for the 2067 Tests that have been played since 1877:
Code: Select all
Country Rating
1 South Africa 2388
2 Australia 2385
3 England 2345
4 India 2296
5 Pakistan 2287
6 Sri Lanka 2267
7 West Indies 2169
8 New Zealand 2151
9 Bangladesh 1902 Here are the current ICC Test Rankings for comparison. The most obvious difference seems to be that Elo fits the teams more closely together than the ICC system.
If Australia beat Sri Lanka in the Boxing Day Test, then Australia will overtake South Africa to become number 1.