section 4.3 exercises 281 simulated difference (a - b) in mean response (b) there is one dot at 0.72…

Brief Explanations:

(b) The dot at 0.72 in the context of the simulated difference (A - B) in mean response indicates that in one of the simulation runs, the difference between the mean response of group A and group B was 0.72. It represents a single - instance outcome of the simulated differences. (c) To determine if the difference in means from part (a) is statistically significant, we would look at how often a difference as extreme or more extreme than the observed difference (from part (a)) occurred in the simulation. If the observed difference (from part (a)) is in the tails of the distribution of simulated differences (i.e., if it is a rare event in the simulation), we can say it is statistically significant. If it is a common value among the simulated differences, it is not statistically significant. However, since the result of part (a) is not given, we can't make a definite conclusion on significance.

Answer:

(b) In one simulation run, the difference between the mean response of group A and group B was 0.72. (c) Without the result from part (a), we cannot determine if the difference in means is statistically significant. We would check if the part (a) difference is a rare or common event among the simulated differences.