How are the ICC cricket ratings calculated

1. What is a rating?

A rating is worked out by dividing the points scored by the match/series total, with the answer given to the nearest whole number. It can be compared with a batting average but with points instead of total runs scored and a match/series total instead of number of times dismissed. After every Test series, the two teams receive a certain number of points, based on a mathematical formula. Each team’s new points total is then divided by its new match/series total to give an updated rating. With batting averages, if you are dismissed in your next innings for more than your average, your average will increase. Conversely, scoring less than your average will cause it to fall. Similarly, under the Reliance ICC Test Championship method, the points earned from a Test win will always be more than the rating the team had at the start of the series. Equivalently, a team losing a Test match will always score fewer points than its rating. So a win will always boost a team’s rating and a defeat will harm it. A draw between a higher and lower rated team will slightly benefit the rating of the lower rated team at the expense of the higher rated team. A draw between two similarly rated teams will leave both their ratings unchanged. A tied match is treated the same as a draw for rating purposes.

2. What does a particular rating signify?

A team that, over the period being rated, wins as often as it loses while playing an average mix of strong and weak opponents will have a rating of close to 100. A rating of 100 could also correspond to a side that wins more often than it loses but who has generally played more matches against weak teams. Similarly, if the majority of its matches are against strong teams, then a rating of 100 could be achieved despite having more defeats than victories. It is quite often the case that there are a number of teams in the 90-110 range. These teams are of broadly similar standard. A rating above 120 suggests consistently strong performances. Above 130 is rarely achieved and suggests a high degree of dominance over all other teams. In every match the total rating points available equals the sum of the initial rating of the two teams, so ratings can be thought of as being redistributed rather than created. There is therefore no ‘inflation’ in this rating system, so a rating of 120 suggests the same degree of superiority over opponents now as in the past or future, and a team can meaningfully compare its rating movements over time.

3. How quickly do ratings change?

The amount by which a rating improves after winning a Test will depend on the rating of the opponent. A win over a much stronger team (i.e. one with a much higher rating) boosts the rating more than beating a much weaker opponent. Conversely, losing to a much stronger team will not cause the rating to drop too far, but losing to a weaker side would. It is possible for a team to win a series yet for its rating to fall. This will happen if a stronger team wins a series but by a smaller margin than the respective ratings suggest should be the case. For example, when Australia played England in a five-Test series in 2002-03, Australia needed to win by a margin of at least three Tests just to maintain its very high rating.

4. How is the series result incorporated?

At the end of any series comprising two or more Tests, a series bonus will be awarded. Like an individual Test match, a series can be won, drawn (tied) or lost. For rating purposes, the series result is equivalent to the result of one further Test. To explain, suppose a team has just won a Test series. The series bonus can be regarded, for rating purposes, as if one extra Test has been played and won by the team that has just won the series. If a series finishes level, the series bonus is equivalent to the two teams playing an extra drawn Test.

5. What period does the table cover?

The table reflects all Test series completed since the annual update made three to four years previously. This pattern is repeated each May, with the oldest of the four years of results removed to be gradually replaced with results of matches played over the following twelve months. Thus once a year, the rankings will change overnight without any new Tests being played. This process, called updating the data, takes place at the start of May each year. This time has been chosen since it is usually a relatively quiet time in the international calendar. Before 2012, the annual update took place in August.

6. How are the results weighted?

All matches included within the Reliance ICC Team Rankings Tables will always fall into one of two time periods:

 Period One covers the earliest two years of matches

 Period Two covers all subsequent series, i.e. the past one to two years Weightings are applied to these two groups of series so that the ratings more fully reflect recent form.

The weightings are as follows:

Period One matches have a weighting of 50 per cent.

 Period Two matches have a weighting of 100 per cent. In the current table, series completed since last May receive a weighting of 100 per cent. After next May, the weighting of series being played now will remain at 100 per cent, while the weighting of series played in the previous year will fall to 50 per cent. The ‘match/series total’ column in the Reliance ICC Test Team Rankings table comprises a combination of individual Tests and series. This total along with the number of points earned in each period is multiplied by the weighting factor. For example, suppose a team played 20 Tests and six series in Period One, plus 15 Tests and five series in Period Two. The total matches played for rating purposes is 50 per cent of (20+6) plus 100 per cent of (15+5), which equals 33. (A small technical adjustment ensures that, for all teams, the total number of matches and rating points is always a whole number.)

7. How does the system compare with the current ODI rating method?

There are a number of similarities between the Reliance ICC Test Team Rankings table and the official Reliance ICC ODI Team Rankings table, and these are summarised as follows:

 The underlying formula that determines the number of points awarded to each team for its performance in an individual match is identical; so as with the ODI system it takes no account of the venue or margin of victory of any match.

 A rating of 100 reflects average performance, so a team winning and losing a similar number of matches and playing a broad mix of opponents will have a rating close to 100.

 The ratings are updated each May, whereby the weightings assigned to older matches are reduced.

The new Reliance ICC Test Team Ranking differs from the official ODI rankings as follows:  In addition to reflecting the performance in every Test, there is also a series bonus, carrying the same weight as one additional Test and awarded to the winner of a series of two or more matches.

 Test draws are treated in the same way as ties in ODIs, even though in character they may be more reminiscent of no results (especially if interrupted by bad weather); only Tests abandoned without a ball bowled would be excluded for rating purposes.

 The ratings are officially updated after each series rather than after each Test

The ICC Player Rankings are a sophisticated moving average. Players are rated on a scale of 0 to 1000 points. If a player’s performance is improving on his past record, his points increase; if his performance is declining his points will go down. The value of each player’s performance within a match is calculated using an algorithm, a series of calculations (all pre-programmed) based on various circumstances in the match.

All of the calculations are carried out using pre-programmed formulae, using the information published in a Test match scorecard. There is no human intervention in this calculation process, and no subjective assessment is made.

Bowlers who do not bowl in a high-scoring innings are penalized.

The players’ ratings are calculated by combining their weighted performance in the latest match with their previous rating. This new ‘weighted average’ is then converted into points. Recent performances have more impact on a player’s rating than those earlier in his career, but all his performances are taken into account. A great player who has had a lean run of form will still have a respectable rating.

Players who miss a Test match for their country, for whatever reason, lose one per cent of their points.

New players start at zero points, and need to establish themselves before they get full ratings. There is a scale for calculating qualifications. For example, a batsman who has played 10 Test innings gets 70 per cent of his rating (i.e. his rating will be between 0 and 700 points). He doesn’t get 100 per cent until he has played 40 Test innings. A bowler who has taken 30 wickets also gets 70 per cent of his full rating. He doesn’t get 100 per cent until he has taken 100 Test wickets. This means that successful new players can enter the top 30 after just a few Tests, but are unlikely to reach the world top five until they have many Test matches under their belts.

The principles behind the ODI Ratings are similar to those for the Test Ratings, with the following important differences:

The Women’s ODI Rankings operate in the same way as the men’s equivalent.  However, statistically there are some differences between men’s and women’s ODI cricket, so there are some adaptations for the women’s version. The average scores in women’s ODIs tend to be lower than in men’s so the points scales were adjusted so as not to favour bowlers, and there are fewer women play ODIs in a given year than men, so there are typically more men bunched within a few points of each other in the table than in the women’s equivalent.