9.The paper towel absorbancy experiment is described on page 303. Three brands of paper towels were

compared (factor A at 3 levels). For each brand, both white and printed towels were evaluated (factor

B, 1 = white, 2 = printed). For each observation, water was dripped from above a towel, which was

horizontally suspended between two pairs of books on a flat surface, until the water began leaking through

to the surface below. The time to collect each observation was measured in seconds. Absorbancy was

measured as the number of water drops absorbed per square inch of towel. The rate at which the water

droplets fell to the towel was measured (in drops per second) as a covariate. The data are reproduced in

Table 9.9.

(a)[3pts] Plot absorbancy versus rate, using the treatment level as the plotting symbol. Based on the plot,

discuss appropriateness of the analysis of covariance model, and discuss whether there appear to be

treatment effects.

(b)[3pts]Fit the one-way analysis of covariance model to the data in which you shall include the treatment

effects and the covariate. Show your SAS code and the ANOVA table.

(c) [2pts] Test for equality of treatment effects, using a significance level a = 0.05.

(d) [2pts] What is the estimate of the slope for the covariate? What does the nagative value of this estimate say

about the effects of rate on the absorbancy? [Hint: consider the solution option in the model statement.]

(e)[2pts] Test the hypothesis H0: B=0 versus H1 : 36= 0 using a significance level a = 0.05, where ß

denotes the slope for the covariate. Find the p-value and state your conclusion.