Use the computer output for the radial keratotomy data of Problem 12 in Chapter 8, along with the additional output here, to answer the following questions.
a. Perform the overall F test for the regression of Y on both independent variables. Interpret your result.
b. Perform variables-added-in-order tests for both independent variables, with X1 added first.
c. Perform variables-added-in-order tests for both independent variables, with X2 added first.
d. Provide a table of variables-added-last tests.
e. Which predictors appear to be necessary? Why?

Transcribed Image Text:

Y Regressed on X1 and X2 Source DF Type 1 SS X1 X2 Mean Square F Value Pr>F 13.09841552 13.09841552 10.67 00020 4.52435640368 0.605 4.52435640 Source DFType ll X1 X2 l SS 12.43080596 4.52435640 Moan Square F Value Pr>F 12 43080596 10.12 0.0025 4.52435640 368 0.0605