Reliance ICC One-Day International Team Rankings -frequently asked questions 

1. What is a rating?
2. What does a particular rating signify?
3. How quickly do ratings change?
4. What period does the table cover?
5. How are the results weighted?
6. Are there any 'rules of thumb' that help explain how a ranking may change?
7. What principles are the ratings based on?

1. What is a rating? 
A rating is worked out by dividing the points scored by the matches played, 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 matches instead of number of times dismissed.

After every ODI, the two teams each receive a certain number of points, based on a mathematical formula. Each team's new points total is then divided by its new matches 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 ODI Rankings method, the points awarded for a win will always be more than the rating the team had at the start of the match.

Equivalently, a team losing an ODI will always score fewer points than its rating. So a win will always boost a team's rating and a defeat will harm it. The ratings therefore give extra meaning to what might otherwise be regarded as 'dead rubbers'. A tie 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 tie between two similarly rated teams will leave both their ratings unchanged. Matches abandoned with no result are always ignored.

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.

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 an ODI 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.

4. What period does the table cover?
The table reflects all ODIs played 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 ODIs 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.

5. 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, matches 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 matches total column in the Reliance ICC ODI Team Rankings table along with the number of points earned in each period is multiplied by the weighting factor. For example, suppose a team played 20 matches in Period One, plus 18 in Period Two. The total matches played for rating purposes is 50 per cent of 20 plus 100 per cent of 18, which equals 28. (A small technical adjustment ensures that, for all teams, the total number of matches and rating points is always a whole number.)

6. Are there any 'rules of thumb' that give me an idea how a ranking may change? 
There are a few "rules of thumb" that may be useful when speculating how a team's rating could change.

Note that the effect would be greater if a team has played fewer matches.

If a team is shown in the table as having played between 30-40 matches then the following would apply:

a) If playing a similarly rated team, a win would typically increase the rating by 1-2 points, while losing would cost 1-2 rating points.

b) If playing a side rated say 20-30 points higher, a win would increase the rating by around 2 points, but a defeat should only cost 1 rating point.

c) If playing a side rated say 20-30 points lower, then the opposite of b) applies - a win might be worth only 1 point, but a defeat might cost 2 points. Finally, it might need two or three wins against a team rated 40 or more points lower to increase the rating by one point, but just one defeat might cost 3 points

7. What principles are the ratings based on? 
 The Reliance ICC ODI Rankings table is based on the following principles:

 i. It is based on individual matches, not on series of matches. While the result of an ODI series will remain important for the competing countries, the ratings treat each match as an entirely separate event. Therefore every ODI will count (apart from No Results) and there is no need for a stipulated minimum series length.

ii. All ODIs are treated equally. Although the ICC Cricket World Cup final will have more at stake than any other match, every ODI is subject to the same formula for ratings purposes.

iii. No account is taken of venue. Whether a side wins an ODI at home, away or at a neutral venue will not affect the ratings. iv. No account is taken of margin of victory. The rating system records only whether a team has won, drawn or tied each match.

v. More recent results have a greater impact than older matches. To ensure the ratings fairly reflect current form, the weighting given to a particular match reduces as times passes.