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 season 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.