PwC cricket ratings

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XODI Extended ODI Cricket Ratings

The XODI cricket ratings are one of a number of different cricket rating systems. Its main claim to difference with other systems is that it focuses on the margin of each game. The effect of this is that, if a strong team plays a weaker team, it needs to win by a certain margin to maintain or improve its ranking. A narrow win could see the stronger team's rating decline.

How the ratings are calculated

Prior to each game, the two teams sacrifice ten percent of their ratings into a pool of points to be divided up between the teams after the game based on the result. The winner gets 20 percent of the pool plus a proportion relative to the winning margin.

NW = 0.9 * OW + 0.1 * (OW + OL) * (0.2 + 0.8 * (RW / (RW + RL))

NL = 0.9 * OL + 0.1 * (OW + OL) * 0.8 * (RL / (RW + RL)

where:

NW is the new rating of the winning team
NL is the new rating of the losing team
OW is the old rating of the winning team
OL is the old rating of the losing team
RW is the modified runs scored by the winning team
RL is the modified runs scored by the losing team

If the winning team bats first and its target isn't revised because of a rain-delay, then RW and RL are the actual runs scored by each team.
If the winning team bats second then its runs scored are modified by multiplying its actual runs scored by the total number of overs available for its innings divided by the actual number of overs faced.
If the game is affected by a rain delay, the runs scored by the team batting first are modified to one less than the revised target and the total available overs are also reduced accordingly if the team batting second wins.

Examples

1. Australia plays Canada in a One Day International. Australia has an initial rating of 4000 so contributes 400 points to the game pool. Canada has an initial rating of only 1000 so only contributes 100 points to the game pool. Australia scores 300 runs then dismisses Canada for 200 runs to win the game. Australia's new rating is:

NW = 0.9 * 4000 + 0.1 * (4000 + 1000) * (0.2 + 0.8 * 300 / (300 + 200))

  = 3600      + 500      * 0.68

  = 3940

So Australia wins the game but were expected to win by a greater margin so their ranking goes down and Canada's goes up by the same amount.

2. India plays Pakistan. Both have initial rankings of 3000 so each contributes 300 points to the game pool. India scores 300 runs in its 50 overs but rain interrupts the Pakistani innings and the Duckworth-Lewis calculation requires Pakistan to score 251 runs in 40 overs. Pakistan reaches 252 halfway through the 38th over.

RL = 251 - 1 = 250 RW = 252 * 40 / 37.5 = 269

NW = 0.9 * 3000 + 0.1 * (3000 + 3000) * (0.2 + 0.8 * 269 / (269 + 250))

  = 2700      + 600      * 0.6146

  = 3069

Notable points

The XODI ratings only cover One Day Internationals (ODIs) and other game played under the conditions of ODIs but between teams not granted full ODI status. The XODI website says it doesn't have a test ranking because there aren't enough two-innings games between the test teams and non-test teams.