Part 2C: Check your understanding: Exploring Example Data

Use the above Greenhouse App to check your understanding

Name (if more than one name, separate each name with a comma)

Instructor's Email Address

A. Use Settings A (above left) for the following Questions. View the R-square values when the Statistical Model is Linear, when it is Quadratic, and when it is set to Cubic. Which of the three R-squared values is clearly different from the others?
Linear Cubic Quadratic
B. What is the coefficient for X² in the quadratic model?
8.66 1.5 -0.15 -11.25
C. When developing regression models, we often search for a parsimonious model. This is a model that is as simple as possible without losing a substantial amount of accuracy. Which model appears to be the most parsimonious when we are predicting corn profits based upon the amount of water used?
Linear Cubic Quadratic
D. What is the p-value for the X² coefficient in the quadratic model?
-0.3 smaller than 0.0001
-11.25 0.82
E. What is the p-value for the X² coefficient in the cubic model?
-0.3 smaller than 0.0001
-11.25 0.82
F. Do the p-values for each model coefficient appear to be reliable measures of the importance of a particular term in the model?
Yes No Not sure
G. Use Settings B for the following Questions. What is the R-squared value for this model?
0.01 0.37 0.84 0.56
H. Using this model, predict the yield for tomatoes when water = 45
0.37 4.8 9.23 12.14
I. Using this model, predict the yield for beans when water = 45
0.37 11.25 12.14 4.8
J. Check the Remove Interaction Terms Box, what is the R-squared value for this model?
0.01 0.37 0.84 0.56
K. What is the equation for this model with no interactions?
Yield = 4.6 + 0.02Water + 0.63Tomato Yield = 4.6 + 0.02Water - 0.63Tomato
Yield = 4.6 - 0.63 Water + 0.02Tomato Yield = 4.6 - 0.01Water - 0.63Tomato