# Variance Comparison and Analysis

11.8 Students in a business course performed a completely randomized design to test the strength of four brands of trash bags. One-pound weights were placed into a bag, one at a time, until the bag broke. A total of 40 bags, 10 for each brand, were used. The data in the trashbags.xls file gives the weight (in lbs.) required to break the bags.

a. at the .05 level of significance, is there evidence of a difference in the mean strength of the four brands of trash bags?

b. if appropriate, determine which brands differ in mean strength

c. at the .05 level of significance, is there evidence of a difference in the variation in strength among the four brands of trash bags?

d. Which brands should you buy, and which brands should you avoid? Explain.

11.12 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 Yield-One Way) are as follows:

New1 New2 Standard

38 29 31

34 35 23

38 34 38

34 20 29

19 35 32

28 37 30

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)?

Data:

KROGER GLAD HEFTY TUFFSTUFF

34 32 33 26

30 42 34 18

40 34 32 20

38 36 40 15

36 32 40 20

30 40 34 20

30 36 36 17

42 43 34 18

36 30 32 19

38 38 34 20

https://brainmass.com/statistics/analysis-of-variance/variance-comparison-analysis-535476

#### Solution Preview

HI there,

Thanks for letting me work on your post. I've included the full explanations in the excel.

a. First, we run "ANOVA: single factor" under "data analysis" in excel and obtain the output on the left. Since P value is 1.12E-12, less than 0.05, we reject null hypothesis and ...

#### Solution Summary

The expert examines variance comparison and analysis. Which brands differ in mean strengths are determined.