A regression analysis of data on n = 53 males considered the following variables:
Y = SBPSL (estimated slope based on the straight-line regression of an individual's blood pressure over time)
X1 = SBP1 (initial blood pressure)
X2 = RW (relative weight)
X3 = X1X2 = SR (product of SBP1 and RW)
The accompanying computer printout was obtained by using a standard stepwise regression program (SPSS). Using this output, complete the following exercises.
a. Fill in the following ANOVA table for the fit of the model Y = β0 + β1X1+ β2X2 + β3X3 + E.

b. Test H0: ρYX2|X1 = 0.
c. Test H0: "The addition of X3 to the model, given that X1 and X2 are already in the model, is not significant."
d. Test H0: ρY(X2, X3)|X1 = 0.
e. Based on the tests in parts (b) through (d), what is the most appropriate regression model? Use α = .05.
f. Based on the information provided, can you assess whether X1 is a confounder of the X2-Y relationship? Explain.
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