Rating of team abilities in soccer

Soccer is a team sport, so measurement of team quality is important. Preferably, quality is measured as a single number that can be used to answer questions such as which soccer team is the best or how do two teams compare to each other. Such questions are asked by fans, players, management of teams and other stakeholders alike. In soccer, the standard to rank teams is by having all teams play a double round robin tournament, with each two teams playing each other twice, once at each venue. Ranking is based on the number of points obtained. However, it is not always practical to play a complete round robin tournament. Moreover, intermediate rankings before all matches in a round robin setup are played reflect both abilities of teams and the matches played so far. As long as not all teams have played each other, it is possible that the team that leads the ranking has had the ‘easiest’ schedule compared with other teams. Intermediate rankings, if available, do not reflect team abilities alone.