Prosthodentists specialize in the use of dental implants, dentures, and crowns.

ID: 3151284 • Letter: P

Question

Prosthodentists specialize in the use of dental implants, dentures, and crowns. Repairing chipped veneer is less time consuming than complete restoration, so a researcher wants to compare four different repair kits (1 = Cojet, 2 = Silistor, 3 = Cimara, and 4 = Ceramix) with respect to the average bond strength. The researcher randomly divided 20 equivalent porcelain veneer specimens into four treatment groups and chipped each specimen (in the same way) so each chip could be repaired with one of the four different repair kits. Each chip repair was evaluated for bond strength (units = MPa, megapascals). Three of the specimens were damaged resulting in the following data.

We vaguely remember that an assumption about normality is required to perform the inference. What is this assumption?

a) The bond strengths for the sample of 17 repaired chips should be normally distributed.

b) The bond strengths for the population of all such repaired chips should be normally distributed.

c) The bond strengths for each of the four samples of repaired chips each should be normally distributed.

d) The bond strengths for each of the four populations of all such repaired chips should be normally distributed.

b) To assess the normality condition, how many QQ plots should be examined?

a) None, since we have a large enough sample size

b) 1 QQ plot for all 17 bond strengths

c) 4 QQ plots, one for each sample of bond strengths for the 4 different repair kits

c) Complete the following statement in reference to this incorrect null hypothesis, H0: x1 = x2 = x3 = x4 .

“No, no! Hypotheses are supposed to be about ____________________ , not ________________."

Select all options that are correct.

a) population means, not sample means

b) population variances, not sample means

c) parameters, not statistics

d) statistics, not parameters

Explanation / Answer