Overtime The National Football League (NFL) has used a sudden death overtime period since 1974 to help decide a winner in games that are tied at the end of regulation time. Before the overtime starts, a coin flip is used to determine which team gets the ball first. Some critics of the system complain that the team that wins the coin flip has an unfair advantage. In the 445 overtime NFL games in the period between 1974 and 2009, the team winning the coin toss has won 240 times and lost 188 times and 17 games have ended in a tie when neither team scored during the overtime. When considering the impact of overtime policy for future games, we’ll consider these games as a sample of all possible NFL games.
(a) Discarding the 17 tie games, we see that the winner of the coin flip has gone on to win 240 of the 428 games where a winner is determined in overtime. Does this provide sufficient evidence to show that the team winning the coin flip has an advantage? Use StatKey or other technology and assume that the league uses a 5% significance level.
(b) The NFL changed a rule before the 1994 season (moving the kickoff line back 5 yards) that might affect this analysis. For 188 games (again ignoring ties) from 1974 to 1993, the winner of the coin flip won 94 times and lost 94 times. In 240 games played between 1994 and 2009 (after the rule change) the winner of the coin flip won 146 games and lost 94. Organize this information in a two-way table and discuss any statistical evidence for a difference in the advantage (if any exists at all) for the team winning the coin flip under the new and old rules.