Use multiple regression with indicator variables, instead of one-way ANOVA, to test whether the quality data in Table 15.1.1 show significant differences from one supplier to another. (You may wish to review the material on indicator variables from Chapter 12.)
a. Create the Y variable by listing all quality scores in a single, long column. Do this by stacking Amalgamated€™s scores on top of Bipolar€™s on top of Consolidated€™s.
b. Create two indicator variables, one for Amalgamated and one for Bipolar.
c. Run a multiple regression analysis.
d. Compare the F statistic from the multiple regression to the F statistic from the one-way ANOVA. Comment.
e. Compare the regression coefficients for the indicator variables to the average differences in quality scores from one supplier to another. Comment.
f. Do these two methods€”multiple regression and one-way ANOVA€”give different answers or are they in complete agreement? Why do you think it works this way?
QUESTION CONTINUE TO NEXT PAGE€¦..

Transcribed Image Text:

TABLE 15.1.1 Quality Scores for Suppliers' Products Amalgamated 75 72 Bipolar Consolidated 87 80 86 80 67 92 75 95 85 86 92 92 85 87 86 92 86 82 72 87 72 76 86 74 86 93 89 83 Average Standard deviation Sample size X, 82.055556 51-71 24 706 X 80.666667 87.6842 1 1 S-7.598245 S 5.228688 n19