Question 13.67

13.67 NFL offense.

In the National Football League (NFL), many argue that rules changes over the years are favoring offenses. Consider a time series of the average number of offensive yards in the NFL per regular season from 1990 through 2013.36

nfloff

  1. Make a time plot. Is there evidence that the average number of offensive yards per game is trending in one direction? Describe the general movement of the series.
  2. Fit a trend model to the data and report the estimated model. What is the interpretation of the coefficient of the trend term in the context of this application?
  3. Based on the trend fit, forecast the average number of offensive yards per game for the 2014, 2015, and 2016 seasons.

13.67

(a) The offensive yards are increasing over time. (b) . The trend term means that the number of offensive yards increases by 1.54596 each year. (c) For 2014: 342.3953. For 2015: 343.9412. For 2016: 345.4872.