10 August 2014

Malaysia at Tromso: Calculating the Tie-Breaks

My wife was asking me how the tie-breaks are calculated to determine the team rankings at the Olympiad. So I thought it would be a good thing to share my explanation with readers of this blog.

Team rankings were traditionally based on game points, i.e. the scores of the individual games. The match result did not matter. Winning 2 matches 4-0 and losing the other 0-4 totals 8 game points. Whereas winning 3 matches by 2.5-1.5 scores total only 7.5 points which is worse.

As the Olympiad is a team event, FIDE thought that match results should be more important. Just imagine for football fans, would you argue that winning 1 match 9-0 and losing 3 others 0-1 (+6 goal difference), is better than winning all 4 matches 1-0 (+4 goal difference).

Thus several Olympiads ago, FIDE changed the basis for team rankings to give priority to match results, 2 points for a win, 1 for a draw and zero for a loss (the Match Points). The game scores were restricted to helping calculate tie-breaks for teams with the same number of match points. After the match points, the next tie-break (TB2 in chess-results) was calculated by multiplying the Match Points of opponents by the score achieved against them. The illustration below uses Malaysia's results up to Round 7:


Malaysia's Round 1 opponent, Spain has 10 Match Points after Round 7. As Malaysia scored 0.5 point (1 draw) against Spain, the TB2 score is 10 x 0.5 = 5 points. The same calculation is done for opponents met in other rounds. Thereafter, the TB2 points from the opponent with the lowest MP is excluded, hence the 10 points from Kenya was excluded from the total in the illustration above.

The figures above show how important the 4-0 score from the Nigeria match is as it contributed the most to Malaysia's TB2 total. As it is expected that there will be many teams finishing with the same number of Match Points (TB1), a high TB2 score can be a difference of a few ranks in the final rankings.

3 comments:

  1. Mr Fong, thanks for the explanation, Now I understand how it is derived.

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  2. Why is Malaysia being paired with Pakistan in Round 8 ? Both are ranked in the lower half of the 8 match pointers ?

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  3. Why Pakistan? is explained in the next post.

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