Qualm Engineering (Vol. 6, 1994) reported the results of an experiment that was designed to find ways to improve the output of an industrial lathe. The lathe is controlled by a computer that automatically feeds bar stock, cuts the stock, machines the surface finish, and releases the part. As it is machined, the bar stock spins and is held in place by a collect. The lathe operator sets the feed (the rate at which bars are machined) and the speed (spin rate). The product characteristic of interest is surface finish. It is measured on a gauge that records the vertical distance a probe travels as it moves along a given horizontal distance on the bar. The rougher the surface, the higher the gauge measurement. The factors that were manipulated in the experiment were speed, feed, collect tightness, and tool wear. The table below reports the factor-level settings and the resulting surface-finish measurements (H = High; L = Low).
a. What type of experimental design was used?
b. How many different treatments were applied?
c. Perform an ANOVA for these data.
d. Do significant interaction effects exist? Test using α = .05. Interpret your results.
e. Is it necessary to perform main effect tests? Why or why not? If so, perform the tests using α = .05.
f. What assumptions must hold to ensure the validity of your results in parts c, d, and e?

Transcribed Image Text:

F-21 12 48 40 2 2 4 2 2 2 40 3 2 2溜72 39 3 2 2 3 87 45 26 51 33 26 014 69 130 62802| 8 4 8 9 0 3 0 3 3 1 7 1 9 1 5 8 7 7 5 6 1 3 6 4 1 570123333384253219 ini-21 2 To HHHHHHHHLLLLLLLLHHHHHHHHLLLLLLLL Top HHHHLLLLHHHHLILL-HILLLLHHHHLLLL HHLLHELLHH, L L H H L L H H L L H H L L H H L L H H L L |