Concept explainers
The relationship between yield of maize (a type of com), date of planting, and planting density was investigated in the article “Development of a Model for Use in Maize Replant Decisions” (Agronomy Journal [1980]: 459-464). Let
y = Maize yield (percent)
x1 = Planting date (days after April 20)
x2 = Planting density (10.000 plants/ha)
The regression model with both quadratic terms (y = α + β1x1 + β2x2 + β3x3 + β4x4 + e where x3 =
- a. If α = 21.09, β1 = 0.653, β2 = 0.0022, β3 = 2.0206, and β4 = 0.4, what is the population regression
function ? - b. Use the regression function in Part (a) to determine the
mean yield for a plot planted on May 6 with a density of 41,180 plants/ha. - c. Would the mean yield be higher for a planting date of May 6 or May 22 (for the same density)?
- d. Is it appropriate to interpret β1 = 0.653 as the average change in yield when planting date increases by one day and the values of the other three predictors are held fixed? Why or why not?
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Chapter 14 Solutions
Bundle: Introduction to Statistics and Data Analysis, 5th + WebAssign Printed Access Card: Peck/Olsen/Devore. 5th Edition, Single-Term
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