Trends in Biomaterials & Artificial Organs (Jan. 2003) published a study of a new bonding adhesive for teeth. The new adhesive (called “Smart bond”) has been developed to eliminate the necessity of a dry field. In one portion of the study, 30 extracted teeth were bonded with Smart bond and each was randomly assigned one of three different bonding times: 1 hour, 24 hours, or 48 hours. At the end of the bonding period, the breaking strength (in MPa) of each tooth was determined. The data were analyzed using analysis of variance in order to determine if true mean breaking strength of the new adhesive differs depending on the length of bonding time.

a. Identify the experimental units, treatments, and response variable for this completely randomized design.

b. Set up the null and alternative hypothesis for the ANOVA.

c. Find the rejection region for the test using α = .01.

d. The test results were F = 61.62 and p-value ≈ 0. Give the appropriate conclusion for the test.

e. What conditions are required for the test results to be valid?