68. The results of a study on the effectiveness of line drying on the smoothness of fabric were summarized in the article Line-Dried vs. Machine-Dried Fabrics: Comparison of Appearance, Hand, and Consumer Acceptance (Home Econ. Res. J., 1984:

27—35). Smoothness scores were given for nine different types of fabric and ve different drying methods:

(1) machine dry, (2) line dry, (3) line dry followed by 15-min tumble, (4) line dry with softener, and (5) line dry with air movement. Regarding the different types of fabric as blocks, construct an ANOVA table.

a. Using a .05 signi cance level, test to see whether there is a difference in the true mean smoothness score for the drying methods.

b. Make a plot like Figure 11.8 with fabric on the horizontal axis. Discuss the result of part

(a) in terms of the plot.

c. Did the two methods involving the dryer yield signi cantly smoother fabric compared to the other three?

Drying Method Fabric 1 2 3 4 5 Crepe 3.3 2.5 2.8 2.5 1.9 Double knit 3.6 2.0 3.6 2.4 2.3 Twill 4.2 3.4 3.8 3.1 3.1 Twill mix 3.4 2.4 2.9 1.6 1.7 Terry 3.8 1.3 2.8 2.0 1.6 Broadcloth 2.2 1.5 2.7 1.5 1.9 Sheeting 3.5 2.1 2.8 2.1 2.2 Corduroy 3.6 1.3 2.8 1.7 1.8 Denim 2.6 1.4 2.4 1.3 1.6