How big is the home field advantage in the National Football League (NFL)? In Exercise 6.240 on page 419, we examine a difference in means between home and away teams using two separate samples of 80 games from each group. However, many factors impact individual games, such as weather conditions and the scoring of the opponent. It makes more sense to investigate this question using a matched pairs design, using scores for home and away teams matched for the same game. The data in NFLScores2011 include the points scored by the home and away team in 256 regular season games in 2011. We will treat these games as a sample of all NFL games. Estimate average home field scoring advantage and find a 90% confidence interval for the mean difference. 

Exercise 6.240

How big is the home field advantage in the National Football League (NFL)? To investigate this question, we select a sample of 80 games from the 2011 regular season61 and find the home team scored an average of 25.16 points with standard deviation 10.14 points. In a separate sample of 80 different games, the away team scored an average of 21.75 points with a standard deviation of 10.33 points. Use this summary information to estimate the mean home field advantage and find a 90% confidence interval for the mean home field advantage, μ_H − μ_A, in points scored.