An experiment was conducted to determine the effect of pressure and temperature on the yield of a chemical. Two levels of pressure (in pounds per square inch, psi) and three of temperature were used:
One run of the experiment at each temperature–pressure combination gave the data listed in the following table.
a Fit the model
b Test to see whether β3 differs significantly from zero, with α = .05.
c Test the hypothesis that temperature does not affect the yield, with α = .05.
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Mathematical Statistics with Applications
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