Exercises 11.98 through 11.104 use the CROPS data file, which contains the U.S. yield (bushels/acre) of corn and soybeans from 1957-2013.23

Question 11.98

11.98 Corn yield varies over time.

Run the simple linear regression using year to predict corn yield.

crops

  1. Summarize the results of your analysis, including the significance test results for the slope and for this model.
  2. Analyze the residuals with a Normal quantile plot. Is there any indication in the plot that the residuals are not Normal?
  3. Plot the residuals versus soybean yield. Does the plot indicate that soybean yield might be useful in a multiple linear regression with year to predict corn yield? Explain your answer.