14.30 Wheat crop yield The following table shows the result of fitting the regression model for predicting wheat crop yield with indicator variables for fertilizer level (low: 0, high: 1) and irrigation level (low: 0, high: 1).

a. Explain why the coefficient of irrigation is the estimated difference in mean wheat crop yield between the high and low levels of irrigation, for each level of fertilizer.

b. Explain why the 95% confidence interval for the difference in mean wheat crop yield between the high and low levels of irrigation is 1.17 { 2.09 (0.4471), with df = 19 for the MS error.

Transcribed Image Text:

Term Constant Coef SE Coef T-Value P-Value 10.1500 0.6470 15.69 0.000 Fertilizer 1.8100 0.7271 2.49 0.022 Irrigation 1.1700 0.4471 2.62 0.017