Strength of schedule

In sports, strength of schedule (SOS) refers to the difficulty or ease of a team's/person's opponent as compared to other teams/persons. This is especially important if teams in a league do not play each other the same number of times.

The strength of schedule can be calculated in many ways. Such calculations are the basis of many of the various tie-breaking systems used in Swiss-system tournaments in chess and other tabletop games. Before the 2004 season, in the American college football Bowl Championship Series (BCS) the SOS was calculated as follows, where OR is the opponents' record, while OOR is the opponents' opponents record.

Other calculations include adding the opponent's power ratings and multiplying them by the number of games, or a modification by assigning weights (higher weights for "stronger" teams).

Furthermore, several more factors may be added, such as the position of the team in the league, the strength of the team's division or conference, which games count in the formula and which do not (vital in the Bowl Championship Series), the locations of the games (see home team and home advantage) and others.

The BCS previously used the SOS in its formula to determine which teams will play in BCS Bowls, and more importantly, to the BCS National Championship Game. On the contrary, several leagues do not incorporate SOS directly into team standings. For most leagues, however, the team standings are typically affected by the overall strength of the conference the team plays in. The strength of the conference largely depends on the amount of NFL players the conference produces. For instance, from 1992-2011, of 1874 college athletes who entered the NFL, roughly 31% came from the SEC compared to only .64% from the MAC-EAST conference. Therefore, playing a team in the SEC would likely increase a team's SOS as compared to playing a team in the MAC-EAST.

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