Problem

Integrated circuits are manufactured on silicon wafers through a process that involves a s...

Integrated circuits are manufactured on silicon wafers through a process that involves a series of steps. An experiment was carried out to study the effect on the yield of using three methods in the cleansing step (coded to maintain confidentiality). The results (stored in ) are as follows:

New1	New2	Standard
38	29	31
34	35	23
38	34	38
34	20	29
19	35	32
28	37	30

Source: Extracted from J. Ramirez and W Taam, “An Autologistic Model for Integrated Circuit Manufacturing,” Journal of Quality Technology, 2000, 32, pp. 254-262.

a. At the 0.05 level of significance, is there evidence of a difference in the mean yield among the methods used in the cleansing steps?
b. If appropriate, determine which methods differ in mean yields.
c. At the 0.05 level of significance, is there evidence of a difference in the variation in yields among the different methods?
d. What effect does your result in (c) have on the validity of the results in (a) and (b)?