A student runs an experiment to study the effect of three different mufflers on gas mileage. He devises a system so that his Jeep Wagoner uses gasoline from a one-liter container. He tests each muffler 8 times, carefully recording the number of miles he can go in his Jeep Wagoner on one liter of gas. After analyzing his data, he reports that the F-ratio is 2.35 with a P-value of 0.1199.
a) What are the null and alternative hypotheses?
b) How many degrees of freedom does the treatment sum of squares have? How about the error sum of squares?
c) What would you conclude?
d) What else about the data would you like to see in order to check the assumptions and conditions?
e) If your conclusion in part c is wrong, what type of error have you made?