FIFA World Ranking system (2006–2018)
The FIFA men's ranking system 2006–2018 was a calculation technique previously used by FIFA for ranking men's national teams in football. The ranking system was introduced by FIFA after the 2006 FIFA World Cup, as an update to an earlier system, and was replaced after the 2018 World Cup with a revised Elo-based system. The system, like the previous ones, is extremely similar to that of a league, though with changes made to ensure that it is still representative of the teams' performance despite playing differing numbers of matches per annum, and  the differing strength of opposition that teams have to face. The factors taken into account are as follows: Teams' actual scores are a result of the average points gained over each calendar year; matches from the previous four years are considered, with more weight being given to recent ones. Origin. The new rankings were compiled in response to criticism from the media. Meetings were attended by FIFA staff and external experts and a large amount of research was conducted by this group, resulting in the new ranking system. The new system was confirmed in Leipzig on 7 December 2005 by  a committee of FIFA executives. Notable changes include the dropping of the home or away advantage and number of goals from the calculation, and the simplification of many aspects of the system. International "A" matches. In October 2012, FIFA released a press circular defining what is considered to be an international "A" match. Win, draw or defeat. In previous years a complicated system of points allocation was used, depending on how strong the opponent was, and how large the loss margin, which allowed weaker losing teams to gain points when playing a much stronger opposition, if they managed to put  up a decent match. With the new system, the points allocation is simpler: three points for a win, one point for a draw, and zero points for a loss, in line with most league systems around the world. In the event of a match being decided by a penalty shootout, the winning team receives two points, and the losing team one point. Until November 2012, in two-legged play-offs, if Team A lost the first leg 2 – 0, then matched the result in the return leg and won after a penalty shootout, it received two points. However, if Team  A won the return leg by one goal only, being eliminated in the process, it received 3 points. FIFA fixed this flaw starting with the November 2012 ranking. Match status. Different matches have different importance to teams, and FIFA has tried to respect this by using a weighting system, where the most significant matches are in the World Cup finals, and the lowest weighted are friendly matches. FIFA states that it wishes to recognise that friendlies are still important, since they make up half of the competitive matches counted in the rankings. FIFA also stated, however, that it did not  plan to make any adjustment for teams that qualify directly for major tournaments. The match status multipliers are as follows: Opponent strength. A win against a very highly ranked opponent is a considerably greater achievement than a win against a low-rated opponent, thus the strength of the opposing team is an important factor. The new system uses an opposition strength factor based on team rankings. The previous system was based on points difference. The formula used is: with the exceptions that the team ranked #1 is given a multiplier of 2, and teams ranked 150th and below are assigned  the minimum multiplier of 0.5. The ranking position is taken from the opposition's ranking in the most recently published FIFA World Ranking before the match is included in the ranking calculation. The rankings published before July 2006 are purely historical and are not used for the new ranking calculation. Instead, FIFA went back as far as 1996 to apply the new formula and is using those new rankings for the current calculations. See the detailed break-down of point totals for teams from the top 20 in the October 2007 rankings. Regional strength. In addition to the opposition strength  multiplier, FIFA considers the relative strength of entire confederations in the calculation. Each confederation is assigned a weighting between 0.85 and 1.0, based on the relative performance of the confederations in the last three World Cups. Their values are as follows: The multiplier used in the calculation is the average of the regional strength weighting of the two teams: FIFA changed the formula used to compute the confederation weightings after the 2010 FIFA World Cup without public announcement. Without this modification, UEFA's multiplier would have dropped for the first time below 1, with CONMEBOL remaining the only confederation with  a multiplier of 1. The confederation weighting for AFC was increased in August 2011 from 0.85 to 0.86 after a computer programmer found an error in FIFA's calculations. Assessment period. Matches played over the last four years (48 months) are included in the calculation, but there is a weighting to put more emphasis on recent results. Previously an eight-year period was used. The date weighting is as follows: If a team exceeds the assessment period without playing a match, it is temporarily removed from the rankings, and is reinstated as soon as it plays a match again. The  most recent team to be temporarily absent from the rankings is São Tomé and Príncipe (reinstated in November 2011, after having been removed in December 2007). Ranking formula. The final ranking points figure for a single match is multiplied by 100 and rounded to the nearest whole number. Results for all matches played in the year are averaged together (assuming at least five matches have been played). The average ranking points for the four previous years, weighted by their multiplier mentioned above, are added together to arrive at the final ranking points. Examples. The following examples use these hypothetical teams  and confederations, and assume the games are played within the last 12 months: A friendly match is played between Amplistan and Bestrudia. Amplistan wins 2–1. Bestrudia gets no ranking points because it lost the game, so all factors are multiplied by zero. Amplistan's 141 ranking points are calculated like this: More examples: Conesto gets more points than Bestrudia for defeating the same team (Amplistan) because of the higher weighting of its confederation.